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Abstract

The objective was to assess the effectiveness of psychosocial interventions in preventing gang membership and gang-related crime among children and young adults under the age of 30. We performed a systematic review and synthesized interventions targeting universal, selective, and indicated populations published between January 2000 and April 2023. We included 42 (seven randomized, 12 nonrandomized, 23 controlled interrupted time series) studies evaluating 33 unique psychosocial interventions. Synthesis without meta-analysis found a preventive effect of psychosocial interventions in middle schools on gang membership. Furthermore, meta-analysis found that focused deterrence strategies prevented gang-involved violence, and that psychosocial support during probation decreased crime recidivism. This systematic review found significant effects of four psychosocial interventions compared to control in reducing future criminality, especially gun violence, among children and young adults. The findings are discussed regarding policy implications and ethical considerations.

Keywords

Organized crime groups, including street gangs, have a profound impact on global violent crime, significantly contributing to public safety concerns and the deterioration of community well-being. Countries like the United Kingdom, the United States, Sweden, and the Netherlands are witnessing significant increases in gang-related activities and memberships, which are directly associated with a rise in serious and violent crimes (Mallion & Wood, 2020; Roks & Densley, 2019; Rostami, 2017). Membership in street gangs is closely linked to higher rates of delinquent behavior (DeLisi et al., 2009; Krohn & Thornberry, 2008). This association significantly increases the probability of an individual's involvement in serious delinquency with greater frequency (Barnes et al., 2010; Curry et al., 2002; Thornberry et al., 2018). The activities of these gangs extend beyond committing crimes; they undermine social cohesion and quality of life (Lane & Meeker, 2000), instilling fear and victimization in communities and highlighting the urgent need for comprehensive measures to counteract the influence of gang culture effectively (Europol, 2024). Recognizing the severity of the issue, the World Health Organization (WHO, 2023) has identified youth violence, including gang involvement, as a critical global public health concern. There seems to be a lack of interventions to prevent gang-related crime among youth that have been rigorously evaluated with significant positive results, and it remains unclear which interventions do work. Systematic reviews of available studies can provide practitioners and policy makers with important guidance when implementing measures to deal with youth involvement in crime by summarizing the available evidence based on high-quality studies that meet scientific criteria. Next, we summarize available systematic reviews on interventions to prevent gang-related crime among youth.

Early attempts to systematically review gang-related interventions have had poor success. Fisher (Fisher, Gardner, et al., 2008; Fisher, Montgomery, et al., 2008) attempted to conduct Cochrane/Campbell systematic reviews of interventions to prevent gang membership and delinquency (searched April 2007). The authors, however, reported that no studies met their selection criteria in terms of program scope and the methodological strength of the evaluation design.

Hodgkinson and colleagues (Hodgkinson et al., 2009) reviewed the available evidence for the effectiveness of multifaceted interventions with more than one type of intervention (searched in January 2006), for example, community engagement in combination with multiagency involvement. The overall conclusion was that comprehensive interventions did not have a statistically significant effect on gang-related crime or antisocial behavior.

In a systematic review of street gang control strategy, evaluation studies were categorized as prevention, gang activity regulation, justice system-based intervention, comprehensive, and holistic (Wong et al., 2012) (searched 2011). Of the 38 included studies, only three were controlled but none produced significant results. In a more recent review, Wong et al. identified six prevention programs but only one study demonstrated significant effects (Wong et al., 2016) (searched August 2014).

In a Campbell review, Higginson and colleagues (Higginson et al., 2015) assessed the evidence on interventions that focus on increasing social capacity to reduce gang membership or rehabilitate gang members outside of the criminal justice system (searched September 2013). No studies were identified that used an experimental or quasi-experimental design.

The only intervention that has produced significant results in a systematic review is focused deterrence. The most recent review (Braga et al., 2018; Braga & Weisburd, 2012) covered research up until 2015 and summarized the results from 12 trials targeting criminally active gangs and nine targeting open-air drug markets. The results indicated a significant effect on criminally active gangs and borderline significant effects on open-air drug markets.

Given the increase in the number of controlled trials in general (Marshall et al., 2021; Ryan Bengtsson, in press) a 10-year gap of synthesized research can seriously bias conclusions about which interventions are effective. Furthermore, it is notable that few studies are conducted outside of North America. This review addresses a critical gap in research with the specific objective to assess the effectiveness of psychosocial interventions in preventing gang membership and gang-related crime among children and young adults.

Method

We performed a systematic review and synthesized studies that evaluated interventions targeting universal, selective, and indicated populations published between January 2000 and April 2023. In conducting the review we followed the PRISMA checklist (Page et al., 2021). A study protocol was registered in PROSPERO (PROSPERO, CRD42022360672) (Gerell et al., 2022).

Eligibility Criteria

Type of Literature and Country of Origin

Only peer-reviewed literature was accepted if written in English, Danish, Norwegian, or Swedish, from Europe, North America, Australia, and New Zealand. Studies from low- and middle-income countries were excluded.

Target Population

The target population should be adolescents and young adults under the age of 30. Studies were excluded if 30% or more of the included participants were 30 years of age or older. The studies included local criminal street gangs. An oft-cited definition in both American and European contexts is “… a durable, street-oriented youth group whose identity includes involvement in illegal activity” (Weerman et al., 2009). Street gangs can further be defined by five essential elements: they consist of three or more persons; typically, teenagers or young adults; they are more than temporary groups; they occupy public space; illegal activities are part of the groups’ identity; often, but not necessarily, they identify with a geographic area. Studies were excluded that dealt with mafia-style groups, clan-related groups, terrorist groups, or outlaw motorcycle gangs.

Interventions

Interventions were included if they were either explicitly stated to prevent gang membership and crime or included an outcome measure that was gang-related (eg, carrying a weapon). The intervention may target universal, selected, or indicated populations, as well as individual, family, or group interventions.

To be included, the intervention had to involve a psychosocial component. By the term psychosocial, we mean a range of approaches that address psychological, social, emotional, or behavioral aspects of an individual's well-being. These interventions can include counseling, therapy, skills training, and social services, typically targeting various aspects of mental health, interpersonal relationships, and social functioning. The goal is to enhance psychological resilience, improve coping skills, and promote overall quality of life (Committee on Developing Evidence-Based Standards for Psychosocial Interventions for Mental et al., 2015). Examples of interventions that were excluded are hotspot policing, surveillance cameras, community policing, and judicial reforms (e.g., curfew and restricted stay zones).

Outcome

For universal and selected prevention, the primary outcome was gang membership (e.g., gang identification, gang involvement, gang affiliation) or gang-related crime (e.g., handgun carrying, homicides, gun violence, shootings, assaults with a firearm). For indicated prevention, the main outcome was homicides and shootings. Secondary outcomes include drug crimes (e.g., drug and narcotics incidents, drug and disorder crimes) and recidivism officially reported by the police or the court (i.e., arrests or convictions).

Study Design

Studies included randomized controlled trials (RCT), nonrandomized studies on intervention effects (NRSI), and controlled interrupted time series (CITS). The latter is particularly useful when a randomized trial is not possible or is unethical. ITS is considered one of the strongest quasi-experimental research designs (Lopez Bernal et al., 2018; 2019; Penfold & Zhang, 2013; Shadish et al., 2001), especially when it includes a control (e.g., another city or district not receiving the intervention in focus). The comparison group in each study could be no intervention (e.g., waitlist control), treatment-as-usual, or another intervention.

Literature Search Strategy

A multidimensional systematic search strategy was formulated, focusing primarily on gangs, gang members, gang crime, and network crime. Several additional search blocks were added in areas described as “gang-related” by the project team. A smaller number of specific interventions known to the project team were also included in this search (for this information we refer to SBU, 2023 appendices or contact the corresponding author).

Throughout the project, many named interventions were identified. As a result, a new and modified search strategy was developed in April 2023, incorporating these interventions (for this information we refer to SBU, 2023 appendices or contact the corresponding author). In the modified search, some other limitations were made. The searches were conducted in the following seven databases:
Academic Search Premier (EBSCO),

Criminal Justice Abstracts (EBSCO),

ERIC (EBSCO), PsycInfo (EBSCO),

Scopus,

Social Services abstracts/Sociological abstracts (ProQuest), and

SocIndex (EBSCO).
A citation search based on 48 studies deemed relevant after the initial literature search was performed in Scopus. The studies were: Boots et al. (2018); Braga (2001); (2008); (2008); (2009); (2014); (2016) ; Brantingham (2021); Buggs et al. (2022); Circo (2021); Clark-Moorman (2019); Cook et al. (2015); Corsaro et al. (2010); (2010); (2013); (2015); Densley (2017) ; Di Placido et al. (2006); Engel (2013); Esbensen et al. (2013); Fox et al. (2015); (2022); Gebo (2022); Grunwald (2017) ; Hawkins (2008); Jeffries (2019); Kitzman et al. (2019); Kochel (2022); Lane et al. (2007); Matthay et al. (2019); McGarrell (2010) ; (2013); Papachristos (2015) ; Park et al. (2021); Phalen (2020); Piehl (2003); Roman (2019); (2020); Saunders et al. (2015); (2017); Spooner et al. (2017); Tapia (2017); Thornberg (2018); Uchida (2019); Valdez et al. (2013); Wallace (2016); Weinrath et al. (2016); Williams et al. (2014).

To identify and manage duplicate publications, we used the EndNote reference system (https://endnote.com/). All studies were housed in Covidence, a web-based application for systematic reviews (https://app.covidence.org). Two authors working pairwise screened each final search result (title and abstract). If either of the two judged that the study met inclusion criteria, the full text was obtained for further review. The full-text article was then reviewed and assessed by two authors. If these two reviewers did not agree on study eligibility, the study was reviewed and discussed by the group of six PhD-level authors until a consensus was reached.

Risk of Bias Assessment and Data Extraction

The risk of bias for RCT and NRSI was assessed independently by pairs of authors using the revised Cochrane risk of bias tools. Discrepancies were resolved by consensus or a third reviewer. To our knowledge, there previously existed no checklists that explicitly assessed the risk of bias in studies using ITS. Based on the aspects assessed in RCT and NRSI, a checklist was constructed (for this information we refer to SBU, 2023 appendices or contact the corresponding author) and tried until deemed reliable (i.e., at least 70% agreement on single items and 100% on the difference between high and moderate/low risk of bias). Discrepancies were resolved by consensus or a third reviewer. Thereafter, data were extracted from the included publications. All recorded extracted data were checked by the authors in pairs and included first after consensus was reached. All decisions were documented.

Grading of Evidence

The certainty of the evidence for outcome measures was assessed according to the Grading of Recommendations Assessment, Development and Evaluation System (Alonso-Coello et al., 2016; Guyatt et al., 2008) with “high certainty” (⊕ÅÅÅ), “moderate certainty” (⊕ÅÅO), “low certainty” (⊕ÅOO), and “very low certainty of evidence” (ÅOOO). Included studies were preliminarily assumed to have the highest possible quality of evidence (⊕ÅÅÅ). Following the assessment of the risk of bias, imprecision, inconsistency, indirectness, and publication bias, points were deducted for failure to meet the demands within each criterion. The grading of evidence was done by consensus.

Statistical Procedure for Meta-Analysis

For the synthesis of quantitative results, meta-analysis was used if possible; otherwise, the results were compiled in a synthesis without meta-analysis (SWiM) (McKenzie & Brennan, 2023). The meta-analysis was performed by using the package meta in R version 4.3.0.

The effect measure to use for the meta-analysis was based on the most commonly used measure in the scientific studies to be included. In some cases, a given effect measure could be converted to another measure (e.g., if the relative risk was used this could be converted to an odds ratio) so that more studies could be combined. The following measures were used:
For focused deterrence, drug market interventions and mediation incidence rate ratio were used.

For correctional care and universal prevention, odds ratio was used.
For a thorough discussion of useful effect measures to use in meta-analyses, see Wilson (2022).

In the meta-analysis, the studies are usually given different weights. Larger studies (which should give more certain results) are usually given more weight. However, the reliability of a study does not depend only on the size of the study. There are several other factors that can affect reliability. It can also be difficult for some studies to calculate exactly what weight they should be given. For the main analyses, the random effects model was used with weights based on the inverse variance method. However, as a sensitivity analysis, extra analyses have been carried out where all studies have been given equal weight. This was accomplished by giving all studies the same standard error. For this analysis, the focus is only on the point estimate of the effect since the confidence intervals are not relevant using hypothetical standard errors. Heterogeneity was studied by using the I² measure.

Synthesis Without Meta-Analysis (SWiM)

Poolings were performed in accordance with guidelines for SWiM (McKenzie & Brennan, 2023) when there was heterogeneity among the included studies, while the interventions were sufficiently conceptually similar. Regarding universal and selective interventions, heterogeneity was observed in several aspects but was particularly noticeable regarding the reported outcome measures, in particular the type of outcome measures across the studies, and how they were defined, analyzed, and presented in the studies. Despite this heterogeneity, some studies were considered sufficiently similar for SWiM to be conducted. In these syntheses, relevant gang-related outcomes were considered. The outcomes that were considered sufficiently similar were grouped within the same outcome category. For each study, the effect was categorized as beneficial or harmful based on the direction of the effect. The direction of effect was assessed based on whether the studies reported results in favor of intervention, in favor of control, or uncertain results. GRADE was used to assess the certainty of the evidence for outcome measures.

Publication Bias

Studies reporting strong significant associations are more likely to be accepted for publication in scientific journals (Ioannidis et al., 2011). Therefore, studies that report nonsignificant results are more difficult to find and may be published only in the so-called “gray literature” (e.g., technical reports, working papers). If this is the case, conclusions may be biased. One way to analyze the publication bias possibility is by using a funnel plot of the distribution of effect sizes. As a rule of thumb, tests for funnel plot asymmetry should be used only when there are at least 10 studies available for inclusion in a meta-analysis (Higgins et al., 2021). Our data met this requirement in one case, focused deterrence.

Results

The literature search identified 18,488 articles for possible inclusion in the systematic review (Figure 1). Furthermore, 57 studies were eligible for quality assessment. After evaluation of the risk of bias, 42 studies remained with sufficient quality (moderate or low risk of bias) (Table 1). All identified studies were published in English. The 42 studies dealing with 33 branded interventions were grouped under three types: universal (five studies), selective (four studies), and indicated interventions (33 studies). The indicated interventions in turn consisted of focused deterrence (n = 13), drug market intervention (n = 5), outreach work and mediation between gangs (n = 5), and interventions within the correctional service (n = 7). In addition, we found three studies that were not like another study and thus were excluded from the synthesis (Koper et al., 2016; Matthay et al., 2019; Williams et al., 2014). Of the 42 studies, seven were RCTs, 12 were NRSIs, and 23 were CITS studies. Furthermore, 39 of the studies were conducted in the United States, two in Canada, and one in Scotland. The studies were published in 27 different journals between 2001 and 2023, with a majority published between 2010 and 2019. For information on characteristics of excluded studies with specified reasons, we refer to SBU (2023) appendices, or contact the corresponding author.

Figure 1.
Flow chart of search results for RCT, NRSI, and ITS studies through the systematic review process.

Table 1.
Characteristics of Included Studies.

Author, year Design Context Intervention Type of intervention Comparison Age range (year), Mean age Males (%) Follow-up (months) Exp_N Cont_N Exp_N at follow-up Control N_at follow-up Primary outcome Secondary outcome

Esbensen et al., 2001* NRSI USA Gang Resistance Education and Training (G.R.E.A.T) Universal, school TAU 6th & 7th grade, M = NI NI 48 NI^a NI NI NI Gang membership (self-report) NR

Ramsey et al., 2003* NRSI USA Gang Resistance Education and Training (G.R.E.A.T) Universal, school TAU 7th grade M = NI NI 2.5 274 148 NI NI Friends being gang member (self-report) Benefits of gang membership (self-report)

Esbensen et al., 2013 RCT USA Revised G.R.E.A.T (Gang Resistance Education and Training) Universal, school TAU 11–13 years, M = NI 50 48 NI^b NI NI NI Gang membership (self-report) Attitudes about gangs (self-report)

Rowhani-Rahbar et al., 2023 RCT USA Communities That Care (CTC) Universal, school TAU 11–18, M = 12.1 years; 49.3 72 2405 2002 2193 1797 Carrying a handgun (self-report) NR

Nieri et al., 2015 NRSI USA Keepin’ it REAL (Refuse, Explain, Avoid, and Leave) Universal, school TAU 10–14, M = 11 years; 46 14 259 322 247 309 Using or carrying a weapon (self-report) NR

Valdez et al., 2013 RCT USA Brief Strategic Family Therapy Selective, family TAU 12–17, M = 15.2 49 6 96 104 54 62 Gang identification (self-report) Conduct Means, (parent reported)

Thornberry et al., 2018 RCT USA Functional Family Therapy-G Selective, family TAU 11–17, M = 15.4 100 6 / 18 62 60 62 60 Gang involvement 6 months (self-reported) Arrested 18 months (register data)

Kitzman et al., 2019* RCT USA Nurse-Family Partnership Selective, family TAU NI, M = 18 49 216 514 228 NI^c NI Gang membership (self-report, maternal and other-caregiver report) Convictions (self-report, maternal and other-caregiver report)

Trulson et al., 2001* NRSI USA STAR (specialized treatment and rehabilitation) Selective, school Intensive supervision program NI, M = 14.5 94.7 12 94 92 94 92 Crime recidivism (register data) 12-month arrests (register)

Braga, 2008 CITS USA Operation Peacekeeper Indicated, focused deterrence TAU NI NI 64 NR NR NR NR Gun homicides (register data) NR

Braga, 2013 CITS USA Operation Ceasefire Indicated, focused deterrence TAU 14–24; M = NI NI 48 NR NR NR NR Gun violence (register data) NR

Braga, 2008 CITS USA Project Safe Neighborhoods Indicated, focused deterrence TAU NI NI 38 NR NR NR NR Gun homicide & Gun-aggravated assault (register data) NR

Braga et al., 2019 CITS USA Operation Ceasefire Indicated, focused deterrence TAU NI NI 48 NR NR NR NR Shootings (register data) NR

Corsaro, 2015 CITS USA Group Violence Reduction Strategy Indicated, focused deterrence TAU NI NI 24 NR NR NR NR Homicide (register data) NR

Papachristos, 2015 CITS USA Group Violence Reduction Strategy Indicated, focused deterrence TAU NI NI 40 NR NR NR NR Shootings (register data) NR

Roman, 2019 CITS USA Group violence intervention Indicated, focused deterrence TAU NI, M = 25.7 NI 24 NR NR NR NR Shootings (register data) NR

Sierra-Arevalo, 2015 CITS USA Project Longevity Indicated, focused deterrence TAU NI NI 18 NR NR NR NR Shootings (register data) NR

Clark-Moorman, 2019 CITS USA Rockford Area Violence Elimination Network (RAVEN) Indicated, focused deterrence TAU NI NI 22 NR NR NR NR Firearm violence (register data) NR

Engel, 2013 CITS USA Cincinnati Initiative to Reduce Violence Indicated, focused deterrence TAU NR NR 42 NR NR NR NR Gang-member involved homicides (register data) NR

Kochel, 2021 CITS USA Focused deterrence Indicated, focused deterrence TAU 17–28, M = 21 NR 17 NR NR NR NR Shootings (register data) NR

Corsaro et al., 2010 CITS USA Indianapolis Violence Reduction Partnership Indicated, focused deterrence TAU 5–24, M = NI NR 24 NR NR NR NR Homicide (register data) NR

Papachristos, 2007 CITS USA Project Safe Neighborhoods Indicated, focused deterrence TAU NR NR 72 NR NR NR NR Homicide (register data) NR

Author, year Design Context Intervention Type of intervention Comparision Age range (year), Mean age Males (%) Follow-up (months) Exp_N Cont_N Exp_N at follow-up Control N_at follow-up Primary outcome Secondary outcome

Corsaro & Brunson, 2013 CITS USA Drug market intervention Indicated, drug markets Other crime types NR NR 14 NR NR NR NR Violent offenses (register data) Drug and disorder crimes (register data)

Corsaro et al., 2013 CITS USA Drug market intervention Indicated, drug markets TAU NR NR 14 NR NR NR NR Aggregated violent offenses (register data) NR

Corsaro et al., 2010 CITS USA Drug market intervention Indicated, drug markets TAU NR NR 24 NR NR NR NR Aggregated violent offenses (register data) Drug crimes (register data)

Saunders et al., 2015 CITS USA Drug market intervention Indicated, drug markets TAU NR NR 24 NR NR NR NR Violent crimes (register data) Drug crimes (register data)

Saunders et al., 2015 CITS USA Drug market intervention Indicated, drug markets TAU NR NR 12 NR NR NR NR Violent crimes (register data) Drug crimes (register data)

Park et al., 2021 NRSI USA Gang Reduction Youth Development Incident Response Program Indicated, mediation TAU NR NI 48 NR NR NR NR Violent retaliation crimes (register data) NR

Fox et al. 2015 NRSI USA Phoenix TRUCE Project Indicated mediation TAU 16–25, M = NI 73 19 NR NR NR NR Shooting (register data) NR

Wilson & Chermak, 2011 CITS USA One Vision One Life Indicated, mediation TAU 15–24, M = NI NI 44 NR NR NR NR Homicides (register data) NR

Buggs et al., 2022 CITS USA Cure Violence/Safe Streets Indicated, mediation TAU 15–34, M = NI 42–50 36 NR NR NR NR Homicides (register data) NR

Corburn et al., 2022 CITS USA Advance Peace Indicated, mediation TAU NI NI 18 NR NR NR NR Gun homicides (register data) NR

Boots et al., 2018 NRSI USA SWIFT Court program Indicated, probation TAU 17–25, M = 19.8 96 24 72 108 72 108 Arrests (register data) NR

Cook et al., 2015 RCT USA Safe Street Prisoner Release Initiative Indicated, prison and probation TAU 0–35, M = 28.3 NI 12 106 130 106 130 Arrest (register data) NR

Di Placido et al., 2006 NRSI Canada High intensity cognitive–behavioral programs Indicated, prison TAU NI, M = 23.7 100 24 40 40 36 34 Recidivism (register data) NR

Spooner et al., 2017 NRSI USA GitRedy Indicated, prison TAU NI, M = 17 96 48 437 179 437 179 Arrest rate (register data) NR

Weinrath et al., 2016 NRSI Canada Spotlight Serious Offender Services Unit Indicated, probation TAU 12–19, M = 15.5 100 12 57 85 57 85 Court convictions (register data) NR

Lane et al., 2007 RCT USA South Oxnard Challenge Project Indicated, probation TAU 12–18, M = 17.5 79 12 264 275 151 163 Violent crimes (self-reported) NR

Braga et al., 2009 NRSI USA Boston Reentry Initiative Indicated, prison and probation TAU 18–32, M = 21.7 100 36 108 309 208 309 Violent crimes (register data) NR

Williams et al., 2014* NRSI Scotland Community Initiative to Reduce Violence Indicated, street workers, community TAU 16–29, M = 17.8 100 24 167 167 124 124 Physical violence (register data) NR

Matthay et al., 2019* CITS USA Operation Peacemaker Fellowship Indicated, fellowship, mentorship, social services TAU NI 100 66 NR NR NR NR Firearm violence (register data) NR

Koper et al., 2016* CITS USA Police-Led Community Initiative to Reduce Gun Violence Indicated, police-community partnership TAU NR NR 9 NR NR NR NR Gun violence (register data) NR

*Not included in synthesis

Synthesis on Universal Interventions

Five studies, two RCTs and three NRSI, evaluated universal school interventions. Three of these studies evaluated an intervention called Gang Resistance Education and Training (G.R.E.AT.), a school-based gang- and violence-prevention program with the goals of teaching youth to avoid gang membership, preventing violence and criminal activity, and assisting youth in developing positive relationships with law enforcement. Two of these described the original version of G.R.E.A.T. (Esbensen et al., 2001; Ramsey et al., 2003), while the third evaluated a major revised version of G.R.E.A.T. (Esbensen et al., 2013). Due to this, only the revised G.R.E.A.T. was considered relevant to include in a synthesis. The revised version of G.R.E.A.T. was evaluated in an RCT involving 3,820 students in 195 classes (31 schools) (Esbensen et al., 2013). Follow-up took place after 4 years and results were based on self-reported data on gang membership and violent offending.

Another school intervention was Communities That Care (CTC) that was evaluated in a cluster-randomized trial involving 24 small towns in the United States, with 12 serving as control (Rowhani-Rahbar et al., 2023). The participants in the study were 4,407 students who had been followed up annually from and including grade 6 through grade 12. School classes were included during grades 5 and 6, which means that the follow-up time varied slightly but was approximately 72 months. The results were based on data on the proportion of students who reported that they were carrying a firearm from grade 6 through grade 12.

The last school study is Keepin’ it REAL (Refuse, Explain, Avoid and Leave). The evaluation was an NRSI involving 581 students in grades 6–7 (Nieri et al., 2015). The comparison group was students who did not participate in Keepin’ it REAL. Results after 14 months are based on self-reported data on carrying or using a weapon in the past 30 days.

Since the school studies deal with different psychosocial interventions with different outcome measures and follow-up time, the results are presented as a Synthesis Without Meta-analysis (SWiM) (McKenzie & Brennan, 2023) (for this information, we refer to SBU, 2023 appendices or contact the corresponding author). Gang membership and carrying weapons were assessed as relevant outcomes. Carrying weapons is considered a typical gang attribute and measures gang membership. The studies included in the synthesis reported the preventive effects of all three school interventions. Note that the two RCTs (Esbensen et al., 2013; Rowhani-Rahbar et al., 2023) also had/ longer follow-up time (48 and 72 months) but presented the exact same effect size, OR = 0.76, while the NRSI with shorter follow-up (14 months) reported an effect of similar size, OR = 0.66 (Nieri et al., 2015).

The overall assessment is that the three school-based interventions (CTC, G.R.E.A.T., and Keepin’ it REAL) can reduce student gang membership, including carrying and use of weapons. The certainty of the evidence was assessed as low (⊕ÅOO) (Table 1), which means that it is possible that the results are correct but that new studies may change the conclusion. Deductions have been made due to the risk of bias (–1.5) and transferability (–0.5).

Synthesis on Selective Interventions

Four selective interventions were identified (Table 1). Two were in all respects but one was similar (Kitzman et al., 2019; Trulson et al., 2001) and two differed markedly (Kitzman et al., 2019; Trulson et al., 2001) and were excluded from synthesis. One study was an 18-year follow-up of an RCT comparing home visits from a nurse during prenatal and infancy periods, compared to treatment as usual (Kitzman et al., 2019). The other study (Trulson et al., 2001) evaluated STAR (Specialist Treatment And Rehabilitation) that applied the concept of boot camp within a school setting. The study, an NRSI, evaluated 182 students, using register data on criminal behavior. For more information on the characteristics of these two studies, see Table 1.

The two similar studies evaluated two family-based interventions: brief strategic therapy (Valdez et al., 2013) and functional family therapy-gang (Thornberry et al., 2018). Except for this difference, the two studies were in all respects similar: target group (antisocial teenagers with gang affiliation or high gang risk), research design (RCT), therapy focus (the family), follow-up time (6 months), control condition (TAU), outcome (self-reported gang involvement), and goal (prevent gang membership).

A SWiM indicated no significant effects of family-based therapy on gang involvement compared to control treatments (for this information, we refer to SBU, 2023 appendices or contact the corresponding author). The evidence was graded as having very low certainty (ÅOOO) due to imprecision and high risk of bias (Table 2).

Table 2.
Summary of Findings Table for Meta-Analyses and Synthesis Without Meta-Analysis Including Grade-Based Certainty of Evidence.

Intervention Outcome Subjects; studies Effect size (95% CI) Grade-based certainty of evidence

Universal prevention School-based programs Gang membership (self-report) n = 8.808 (2 RCT, 1 NRSI) Positive effect on gang membership Low certainty of evidence (⊕⊕○○ −1.5 Risk of bias^a
–0.5 Indirectness^b

Selective prevention Family-based therapy Gang membership (self-report) n = 264 (1 RCT, 1 NRSI) Not possible to determine Very low certainty of evidence (⊕○○○) −1.5 Risk for bias^c
−2 Imprecision^d

Indicated prevention Focused deterrence Firearm violence (registry data) n = NR (13 CITS) IRR = 0.74 (95% CI, 0.67–0.81). Moderate certainty of evidence (⊕⊕⊕○) –1 Publication bias^e

Indicated prevention Drug market intervention Firearm violence (registry data) n = NR (5 CITS) IRR = 0.98 (95% CI, 0.81–1.15) Very low certainty of evidence (⊕○○○) –2 Risk of bias^f
–1 Imprecision^g

Indicated prevention Drug market intervention Drug crime (registry data) n = NR (4 CITS) IRR = 0.65 (95% CI, 0.43–0.88). Low certainty of evidence (⊕⊕○○) –2 Risk for bias^f

Indicated prevention Outreach programs to enhance mediation Firearm violence (registry data) n = NR (2 NRSI, 3 CITS) Not possible to determine Very low certainty of evidence (⊕○○○) −1 Risk for bias^h
−2 Heterogeneityⁱ

Indicated prevention Correctional services in prison Crime recidivism (registry data) n = 693 (2 NRSI) OR = 0.59 (95% CI, 0.16–2.16) Very low certainty of evidence (⊕○○○) −1 Risk for bias^j
−2 imprecision^k

Indicated prevention Correctional services on parole Crime recidivism (registry data) n = 1.678 (5 NRSI, 2 RCT) OR = 0.56 (95% CI, 0.41–0.76) Low certainty of evidence (⊕⊕○○) −1 Risk for bias^l
−1 Indirectness^m

a
Risk of bias: Difficulty with blinding. Large dropout in one study that probably did not have a large impact on the estimated effect. Risk of subjective assessment for self-reported data.

b
Lack of transferability: Possible contextual differences.

c
Risk of bias: Risk that the dropout in a study affected the estimated effect. Risk of baseline imbalances in a study. Risk of subjective assessment for self-reported data.

d
Lack of precision: Few studies and participants, nonsignificant results.

e
Risk of publication bias.

f
Risk of bias: Unclear description of the approach. There may be remaining unknown confounding factors that affect the results. Incorrect or incomplete analysis data in some studies.

g
Lack of precision: The result is not statistically significant.

h
Risk of bias: Unclear description of approach; there may be residual unknown confounding factors affecting the result.

i
Lack of consensus: The results go in different directions.

j
Risk of bias: Risk that difficulties with blinding affected the estimated effect.

k
Lack of precision: The result is not statistically significant, large confidence interval in one of two studies.

l
Risk of bias: Large dropout and risk of subjective assessment in self-reported data in one study.

m
Lack of transferability.

Synthesis on Indicated Interventions

Focused Deterrence

Focused deterrence interventions are aimed at influencing the criminal behavior of individuals through the strategic application of enforcement and social service resources to facilitate desirable behaviors (Kennedy, 2006). A total of 13 studies (Table 1) evaluated focused deterrence, although divided over 10 named interventions. All 13 studies came from the United States with the primary outcome measure of gun violence, either fatal or nonfatal. The study design was controlled interrupted time series (CITS), with TAU as a comparator. The follow-up period varied between 17 and 72 months (M = 37 months).

The meta-analysis (Figure 2) showed a significant effect in favor of the intervention group, IRR = 0.74 (95% CI, 0.67–0.81). The combined result means that the intervention group had a 26% lower incidence of firearm violence during the follow-up period compared to the control group. A sensitivity analysis where all studies were given the same weight (i.e., all studies were assumed to have the same standard error) produced a similar result: IRR = 0.70 (for this information we refer to SBU, 2023 appendices or contact the corresponding author).

Figure 2.
Effect (incidence risk rate) of focused deterrence on gun violence measured with officially reported data.

Since the follow-up period of the studies varied between 17 and 72 months, we investigated whether the length of the follow-up period was significantly related to the incidence rate. The studies are divided into a follow-up period of up to 2 years (on average, 21 months), or longer than 2 years (on average, 52 months). The subgroup analysis shows approximately the same results for follow-up times longer than 2 years (IRR = 0.77) and up to 2 years (IRR = 0.72) (for this information we refer to SBU, 2023 appendices or contact the corresponding author).

We also examined if there was a difference between studies with outcomes that specified homicides (n = 7) or firearm violence without specifying fatalities (n = 6). A subgroup analysis (for this information we refer to SBU, 2023 appendices or contact the corresponding author) reveals almost the same values for both outcome measures: IRR = 0.74 (homicides) and IRR = 0.75 (gun violence without death).

Using a funnel plot, the existence of publication bias was investigated (for this information we refer to SBU, 2023 appendices or contact the corresponding author). The results indicate a lack of small studies with nonsignificant results. Adjusting for the bias that may arise due to publication bias, using a trim-and-fill analysis (Shi & Lin, 2019), our result remains statistically significant, but the effect drops from IRR = 0.74 to IRR = 0.81. Although the statistical measures show some heterogeneity, the results consistently show that focused deterrence reduces gun violence. The evidence was graded as having moderate certainty (⊕ÅÅO) (Table 2).

Drug Market Intervention (DMI)

A second type of focused deterrence strategy focuses on reducing crime driven by street-level drug markets. DMI identifies street-level dealers and presents a deterrence-based message aimed at low-level drug-market offenders. This message was coupled with an offering of a broad array of services for the offenders (National Network for Safe Communities, 2015).

Five studies (Table 1) evaluated DMI (Corsaro & Brunson, 2013; Corsaro et al., 2013; Corsaro et al., 2010; Saunders et al., 2015; Saunders et al., 2017). All studies used CITS and compared the results against other cities or districts that did not implement DMI. The follow-up time varied between 12 and 25 months (M = 18 months). The primary outcome measure was firearm violence (five studies) and a secondary outcome measure was drug offenses (four studies). In both cases, the studies were based on registry data.

The methods used by the various studies differed markedly. This made it difficult to obtain comparable standard errors. We therefore chose to assign all studies the same weight. This made the confidence intervals uninterpretable because they were based on hypothetical standard errors. The meta-analysis (Figure 3) showed no statistically significant difference in firearm violence between the DMI and the control condition, IRR = 0.96 (95% CI, 0.84–1.09). A sensitivity analysis with the actual standard errors produced the same, IRR = 0.96 (for this information we refer to SBU, 2023 appendices or contact the corresponding author). The evidence was graded as having very low certainty (ÅOOO) because of the high risk for bias and imprecision (Table 2).

Figure 3.
Effect (incidence risk rate) of drug market intervention on gun violence.

The meta-analysis reports a significant effect on the incidence of drug crime for DMI, IRR = 0.64 (95% CI, 0.40–0.87). After an average of 18 months, drug crime was 36% lower with DMI compared to the control option. A sensitivity analysis with the actual standard errors produced virtually the same, IRR = 0.64 (for this information we refer to SBU, 2023 appendices or contact the corresponding author). The overall assessment was that DMI can possibly reduce the number of drug crimes. The certainty of evidence was graded as low because of high risk for bias (⊕ÅOO) (Table 2) (Figure 4).

Figure 4.
Effect (incidence risk rate) of drug market intervention on drug crime.

Outreach Programs to Enhance Mediation

Five studies evaluated outreach programs to identify conflicting gangs that were offered mediation to defuse a conflict that otherwise might escalate into violence. In addition, all five studies included social support for those in need. The study design in three cases was CITS (Buggs et al., 2022; Corburn et al., 2022; Wilson & Chermak, 2011) and in two cases was NRSI (Fox et al. 2015; Park et al., 2021). The follow-up period was between 18 and 48 months (M = 33). The comparison group in all cases consisted of standard treatment and the primary outcome measure was firearm violence. All five studies were difficult to interpret due to insufficient or contradictory statistical information.

The Safe Streets/Cure Violence evaluation included seven areas of mediation compared to one synthetic control (Buggs et al., 2022). The effect varied from a 21% decrease in gun violence to a 112% increase. Four areas had a decrease, and three areas had an increase. The conclusion was that this study showed heterogeneous results.

The Advance Peace evaluation covers three areas of mediation and a large area of control (Corburn et al., 2022). The results presented are contradictory. First, results are presented showing that firearm violence decreases by 18.2% for the four areas combined, while it increases by 8.7% for control areas. Results are then reported based on regression analysis where the reduction is greater in the entire area compared to just the intervention areas. However, the summary assessment is that the results point to a positive intervention effect.

The evaluation of One Vision (One Life) assessed the effect of mediation in three neighborhoods and one control neighborhood (Wilson & Chermak, 2011). The results pointed in different directions in the three areas of mediation, from a slight increase in fatal shootings to a slight decrease. However, none of the changes were statistically significant.

The Phoenix Truce evaluation showed a significant increase in gun violence in the mediated area compared to the three control areas (Fox et al. 2015). That result has been supplemented with a regression analysis that controlled for other factors and whose results showed a negative effect on mediation. The negative effect was about an 80% increase in shootings, which seems an unlikely treatment effect.

The GRYD IR evaluation reported a 14.2% reduction in gang violence in the area with mediation compared to the control area (Park et al., 2021). However, the authors did not present any information on whether the reduction was statistically significant or how large the confidence interval was for the reduction in gang violence.

Taken together, these five evaluations did not provide a consistent picture of the impact of outreach to mediate between gangs: two reduced gun violence, one increased gun violence, and for two had no clear effect at all. Considering the uncertainties in analysis, we refrained from a meta-analytic approach and concluded that it is not possible to determine what effect mediation has (ÅOOO) (Table 1).

Correctional Services

Seven studies dealt with correctional services for youth or young adults belonging to gangs or with a history of serious violent behavior (Table 1). All studies involved collaboration between correctional services and social services. Two of the studies offered social services only during enforcement in the correctional facility (Di Placido et al., 2006; Spooner et al., 2017), three only during probation (Boots et al., 2018; Lane et al., 2007; Weinrath et al., 2016), and two in both prison and probation (Braga et al., 2009; Cook et al., 2015). Regardless of format, the experiment interventions had a focus on psychosocial support (e.g., substance use treatment, education, health counseling, and housing).

Two of seven studies were RCT studies (Cook et al., 2015; Lane et al., 2007), and the other five were NRSI. Five studies came from the United States and two from Canada (Di Placido et al., 2006; Weinrath et al., 2016). All seven interventions involved collaboration between correctional services and social services, in five cases also with the police, and in four cases with healthcare. The mean age in the seven studies varied between 15.5 and 28.3 years (mean 20.4 years).

For all studies, the primary outcome measure was crime recidivism regardless of type based on registry data. Since the outcome was dichotomous on the individual level, the odds ratio was chosen as the outcome measure. In six of seven studies, the measure was arrests and in one case, conviction. All studies used TAU as a control option. The studies had different follow-up periods, between 12 and 48 months. To create comparability, we chose recidivism after approximately 12 months. Not all studies presented exactly that time, but it was possible to obtain a close estimate.

The two RCT studies and five NRSI studies are presented in Figure 5. All studies were judged to have a moderate risk of bias. The two RCT studies had the same average odds ratio (OR) as the five NRSI studies: 0.60. Overall, there was no clear pattern that could explain the variation in OR. Although the result varied from an odds ratio of 0.26–1.01, there was no significant heterogeneity, i²= 43%, τ²= 0.0815, p = .10. The assessment was therefore that the overall results for the studies with RCT design and NRSI design were equivalent. RCT studies are normally reported separately from NRSI studies but refer to Cuello-Garcia (Cuello-Garcia et al.); in this case, they were part of a joint synthesis. By analyzing the two types of studies together, the statistical power of the analysis increased.

Figure 5.
Effect (odds ratio) of multicomponent gang reentry programs on crime recidivism.

Two NRSI studies dealt solely with in-custody interventions (Di Placido et al., 2006; Spooner et al., 2017). The meta-analysis (Figure 6) did not result in a statistically significant difference, which means that it was not possible to determine whether incarceration alone influences criminal recidivism after release (ÅOOO) (Table 2).

Figure 6.
Effect (odds ratio) of correctional treatment of gang members in prison on crime recidivism.

Two RCT studies and three NRSI studies described the effect of psychosocial interventions during probation, or during probation and prison. Figure 7 reports the effects of the five studies included in three meta-analyses: first the two studies that combined prison and probation (Braga et al., 2009; Cook et al., 2015), second the three probation studies (Boots et al., 2018; Lane et al., 2007; Weinrath et al., 2016), and finally one that summarized the results of all five studies. The three meta-analyses found significant effects, respectively, OR = 0.59 (95% CI, 0.38–0.91), 0.52 (95% CI, 0.30–0.88), and 0.56 (95% CI, 0.41–0.76). The overall assessment was that psychosocial interventions during probation possibly can reduce the number of criminal recidivisms (⊕ÅOO) (Table 2).

Figure 7.
Effect (odds ratio) of multicomponent gang probation programs on crime recidivism.

Additional Single Study Results

Three single studies investigated the effects of various interventions on gun violence or physical violence (Table 1) (Koper et al., 2016; Matthay et al., 2019; Williams et al., 2014). The evidence across all studies was graded as having very low certainty (ÅOOO). We refrained from combining these effect sizes for meta-analysis due to substantial variation in intervention, follow-up time, design, and outcome measure.

Discussion and Applications to Practice

This systematic review identified four psychosocial interventions that prevent gang membership and gang-related crime, thus increasing the number of evidence-based interventions. Furthermore, two psychosocial interventions did not receive empirical support, which underlines the importance of controlled research to avoid ineffective or even harmful interventions (e.g., Petrosino et al., 2013; Welsh & Rocque, 2014).

The first of the effective interventions include universal interventions in middle school (G.R.E.A.T., Communities That Care, Keepin’ it REAL). The studies indicated that the three interventions decreased the risk of gang affiliation after 14, 48, and 72 months, respectively. It is worth noting that the two studies with the longest follow-up produced the same effect size (OR = 0.76), while the one with 14 months follow-up was somewhat stronger (OR = 0.66).

Of the four indicated interventions, three produced significant effects. The first, focused deterrence, based on 13 studies, reduced gun violence by 26% over an average of 37 months. This result parallels that of the meta-analyses of Braga and colleagues (Braga et al., 2018). Their review covered research up to 2015 with similar research questions as ours. Their meta-analysis demonstrated a significant effect of the intervention, but also with variation between different studies, like ours. It was not considered appropriate to compare ours and Braga and colleagues’ effect sizes because of different measures (Wilson, 2022).

The second indicated intervention is drug market intervention (DMI). Five studies have evaluated the effect of firearm violence, but without providing a statistically reliable result. This is consistent with a meta-analysis which showed that increased police efforts against drug markets lead to increased violence and more murders (Werb et al., 2011). One explanation for this paradoxical result is that removing leading people in the drug trade opens the way for other individuals and gangs to take over the void that has arisen. To maintain control against others who try to establish themselves requires violence. In the previously referenced review of focused deterrence (Braga et al., 2018), DMI had a weak effect bordering on being statistically significant (p < .046). The difference between this and our results might be because the previous review was based on a mixture of different types of crime (e.g., drug crimes, theft, assault, and homicide), while our review included only gun violence.

Although DMI did not affect gun violence, it reduced drug crime by 35% over an average of 18 months. According to Braga et al. (2018), research indicates no displacement and diffusion effects on criminal behavior to other locations. This is consistent with place-based interventions against crime more often leading to crime reductions in nontreated nearby locations rather than displacing crime there (Braga et al., 2019).

The third indicated intervention focused on correctional services for youth or young adults belonging to gangs or with a history of serious violent behavior. Five studies described the effect of psychosocial interventions during probation or during probation and prison. Three meta-analyses yielded the same result, indicating that psychosocial support during probation can reduce the number of criminal recidivisms by 44% during a follow-up time equaling 12 months. Two studies dealt solely with in-custody interventions. The meta-analysis did not result in a statistically significant difference.

The fourth indicated intervention is mediation offered to conflicting gangs. Taken together, the five evaluations did not provide a consistent picture of the impact of mediation between gangs with a follow-up time of at least 18 months: two reduced gun violence, one increased gun violence, and two reported no effect. Due to insufficient or contradictory statistical information, we refrained from a meta-analytic approach and concluded that it was not possible to determine the effect of mediation.

Gang affiliation, and the criminality by and against individuals in such groups, is challenging for many countries. This situation is reinforced by the lack of evidence-based interventions to prevent such negative outcomes. When young individuals are involved in gangs, the matter is morally pressing (UN, 1989), with high stakes involving significant physical and mental health consequences. In the absence of evidence, practitioners are faced with a situation where they risk implementing ineffective interventions or, in the worst case, interventions with negative effects (cf. the Scared Straight programs; Petrosino et al., 2013). The pressing nature of the problem, in combination with a legal obligation for the authorities to intervene and where the decision of how to act rests with the authorities, creates a situation where decisions must be made under great uncertainty.

When there is a lack of evidence, precautionary reasoning can be used. This kind of reasoning has been used to legitimize interventions with weak evidence that sometimes include infringements on people's liberty and rights (Ashworth & Zedner, 2014; Stacey et al., 2017). A sound application of the precautionary principle generally entails limiting, postponing, or refraining from implementing unproven interventions while awaiting assessment (Munthe, 2011). However, sometimes the pressing nature of the problem requires immediate action. In such cases, the interventions still need to be evaluated. There should also be a preparedness to act on the result of such evaluations, so that inefficient or, in the worst case, counterproductive interventions are abandoned. The assessment should also include potential social risks of the interventions, such as increased social tensions and distrust (Hardy, 2017).

From a policy perspective, this review imparts guidance. While some uncertainty regarding efficiency in, for instance, a European context remains, the available evidence provides reasons for cautious implementation with an appropriate evaluation process. If these measures turn out to be unsuitable or insufficient, other interventions can be considered. Any implementation of interventions for which evidence is lacking should be combined with a process of local evaluation (e.g., decide on the appropriate outcome measure, follow-up time, and responsible data collection) since the intervention may be turn out to be effective although no scientific study has yet demonstrated this. A particular aspect of importance is that the local evaluation includes all collaborative parties in the case of inter-agency collaboration (e.g., a collaborative gang intervention project between social service authorities, police, and prison and probation services).

There are further ethical considerations which may affect how, or even if, an intervention should be implemented. Interventions that target specific individuals or groups may thus treat them as, or signal to others that, these are criminals. When deciding which interventions to implement, a balance needs to be struck between targeting as many future criminals as possible, and minimizing targeting innocents so as to avoid undue burdens and intrusions of autonomy and privacy as well as unjustified stigma and loss of trust (Ferzan, 2014). There are also concerns about indirect discrimination if some groups are more burdened by the interventions than others, in particular groups that are, or have been, subject to injustices (Lippert-Rasmussen, 2022). Roman (Roman), for example, raises a concern regarding focused deterrence strategies and emphasizes that particular attention needs to be paid to how the burdens of the intervention are distributed and wonders whether “… GVI—a gang violence reduction intervention that relies on the heavy threat of punitive law enforcement action—has a place in cities today?”

Some interventions have, or could have, coercive elements. Standard requirements for when coercion is justified is that it should be necessary to prevent harm to others, that no less restrictive (but similarly effective) alternative is available, and that it should be proportional to the harm it seeks to prevent (Ashworth & Zedner, 2014). Since these interventions are, to a large extent, aimed at children, coercion may also be justified in the child's best interest but then a balance needs to be struck between the child's best interest, their autonomy, and parental authority.

Most results were graded as very low or low certainty of evidence. It stresses the importance of more controlled evaluations to reduce the risk of using interventions without significant effect. The two subgroup analyses of focused deterrence (short or long follow-up time and outcomes in the form of firearm violence with or without homicide) might guide the designing of new studies since they yield essentially the same outcome. If this result is correct, 21 months of follow-up is enough to secure a valid result on long-term effects, which decreases the timeframe of outcome research. The analysis also indicates that firearm violence without specification of outcome, and homicide, are equally valid as an outcome measure. Merging the two types of outcome research has the potential to produce more exact point estimates, thereby increasing statistical significance.

This review has some strengths and limitations. The strength of this review is that it has followed rigorous systematic review methods, including a comprehensive literature search, independent assessment of studies, assessment of risk of bias, and grading of evidence. The review also has limitations. The first deals with the complexity of identifying studies that include gang-related populations and avoiding the multitude of studies preventing juvenile delinquency in general. Our strategy was to include only those studies that either stated an aim of preventing gang crime or that included a typical gang-related outcome (e.g., carrying a gun). However, there might be other interventions against gang-related crime that our inclusion criteria missed.

A second limitation is the possibility of publication bias. Although we included seven databases and more than 18,000 references, it is still possible that there are unpublished trials that this review missed. This is supported by our analyses on focused deterrence, using a funnel plot. However, using trim and fill technique, the effect was somewhat lower but still statistically significant. We refrained from including “gray” literature such as dissertations and technical reports, because of the challenge to comprehensively identify all gray literature. We identified 20 studies in previous reviews that constitute gray literature (mainly technical reports). In most cases, 18 out of 20, the studies have also been published in peer-reviewed journals with a delay of one or more years. This indicates that time-lag bias is a larger problem than publication bias.

Third, a common challenge in intervention research is the lack of information on implementation quality. This also applies to the studies in this report. With flawed implementation, effective intervention risks appear ineffective. Another problem is the lack of description of the components of interventions; in which order they are given and with what dose. All indicated interventions studied here consist of several components but without a detailed description. Regarding the reliability of the reported results, 33 of 42 are based on criminal record data that is considered to have reasonably high reliability (eg, homicide, gun violence). The other nine studies concern universal and selective interventions and are based on self-report data of unknown reliability.

At last, of the 42 studies identified, 39 represented were from the United States. This raises the question of whether the results are valid for other nations and contexts. Although it is easy to find examples of seemingly important differences between the United States and other nations (e.g., the general level of gun violence), empirical differences do not necessarily tell us about transferability. One example of this is individual placement and support (IPS) that provides support for the competitive employment of patients with severe mental illness. A random-effects meta-regression, including 27 RCTs from different contexts, found that the efficacy of IPS was equal in Europe and the United States (Brinchmann et al., 2020).

Evidence from this review suggests that it is possible to reduce crime, but that the effect is limited. This suggests that the reviewed interventions do not contain all the components needed to create strong effects. Therefore, theory in combination with empirical research is needed to enhance our understanding of what drives change and what does not. For example, if there are components that can be excluded, it will save resources. This work is made difficult by the fact that necessary information on the components of experimental interventions and control conditions is often missing or vaguely described. It is important to document in a protocol or manual so that the content of the intervention can be used as intended. Also, many included studies lacked distinct descriptions of the comparison condition. Based on research examining common components across different intervention formats (van der Pol et al., 2019), intervention research should attempt to delineate components and methods most likely to affect outcome. Also, many of the reviewed studies lacked information on the scope and quality of program implementation as well as descriptions of the comparison condition. This reinforces the importance of increased transparency to allow analyses of how implementation and control characteristics may moderate client outcomes.

Author, year	Design	Context	Intervention	Type of intervention	Comparison	Age range (year), Mean age	Males (%)	Follow-up (months)	Exp_N	Cont_N	Exp_N at follow-up	Control N_at follow-up	Primary outcome	Secondary outcome
Esbensen et al., 2001*	NRSI	USA	Gang Resistance Education and Training (G.R.E.A.T)	Universal, school	TAU	6th & 7th grade, M = NI	NI	48	NI^a	NI	NI	NI	Gang membership (self-report)	NR
Ramsey et al., 2003*	NRSI	USA	Gang Resistance Education and Training (G.R.E.A.T)	Universal, school	TAU	7th grade M = NI	NI	2.5	274	148	NI	NI	Friends being gang member (self-report)	Benefits of gang membership (self-report)
Esbensen et al., 2013	RCT	USA	Revised G.R.E.A.T (Gang Resistance Education and Training)	Universal, school	TAU	11–13 years, M = NI	50	48	NI^b	NI	NI	NI	Gang membership (self-report)	Attitudes about gangs (self-report)
Rowhani-Rahbar et al., 2023	RCT	USA	Communities That Care (CTC)	Universal, school	TAU	11–18, M = 12.1 years;	49.3	72	2405	2002	2193	1797	Carrying a handgun (self-report)	NR
Nieri et al., 2015	NRSI	USA	Keepin’ it REAL (Refuse, Explain, Avoid, and Leave)	Universal, school	TAU	10–14, M = 11 years;	46	14	259	322	247	309	Using or carrying a weapon (self-report)	NR
Valdez et al., 2013	RCT	USA	Brief Strategic Family Therapy	Selective, family	TAU	12–17, M = 15.2	49	6	96	104	54	62	Gang identification (self-report)	Conduct Means, (parent reported)
Thornberry et al., 2018	RCT	USA	Functional Family Therapy-G	Selective, family	TAU	11–17, M = 15.4	100	6 / 18	62	60	62	60	Gang involvement 6 months (self-reported)	Arrested 18 months (register data)
Kitzman et al., 2019*	RCT	USA	Nurse-Family Partnership	Selective, family	TAU	NI, M = 18	49	216	514	228	NI^c	NI	Gang membership (self-report, maternal and other-caregiver report)	Convictions (self-report, maternal and other-caregiver report)
Trulson et al., 2001*	NRSI	USA	STAR (specialized treatment and rehabilitation)	Selective, school	Intensive supervision program	NI, M = 14.5	94.7	12	94	92	94	92	Crime recidivism (register data)	12-month arrests (register)
Braga, 2008	CITS	USA	Operation Peacekeeper	Indicated, focused deterrence	TAU	NI	NI	64	NR	NR	NR	NR	Gun homicides (register data)	NR
Braga, 2013	CITS	USA	Operation Ceasefire	Indicated, focused deterrence	TAU	14–24; M = NI	NI	48	NR	NR	NR	NR	Gun violence (register data)	NR
Braga, 2008	CITS	USA	Project Safe Neighborhoods	Indicated, focused deterrence	TAU	NI	NI	38	NR	NR	NR	NR	Gun homicide & Gun-aggravated assault (register data)	NR
Braga et al., 2019	CITS	USA	Operation Ceasefire	Indicated, focused deterrence	TAU	NI	NI	48	NR	NR	NR	NR	Shootings (register data)	NR
Corsaro, 2015	CITS	USA	Group Violence Reduction Strategy	Indicated, focused deterrence	TAU	NI	NI	24	NR	NR	NR	NR	Homicide (register data)	NR
Papachristos, 2015	CITS	USA	Group Violence Reduction Strategy	Indicated, focused deterrence	TAU	NI	NI	40	NR	NR	NR	NR	Shootings (register data)	NR
Roman, 2019	CITS	USA	Group violence intervention	Indicated, focused deterrence	TAU	NI, M = 25.7	NI	24	NR	NR	NR	NR	Shootings (register data)	NR
Sierra-Arevalo, 2015	CITS	USA	Project Longevity	Indicated, focused deterrence	TAU	NI	NI	18	NR	NR	NR	NR	Shootings (register data)	NR
Clark-Moorman, 2019	CITS	USA	Rockford Area Violence Elimination Network (RAVEN)	Indicated, focused deterrence	TAU	NI	NI	22	NR	NR	NR	NR	Firearm violence (register data)	NR
Engel, 2013	CITS	USA	Cincinnati Initiative to Reduce Violence	Indicated, focused deterrence	TAU	NR	NR	42	NR	NR	NR	NR	Gang-member involved homicides (register data)	NR
Kochel, 2021	CITS	USA	Focused deterrence	Indicated, focused deterrence	TAU	17–28, M = 21	NR	17	NR	NR	NR	NR	Shootings (register data)	NR
Corsaro et al., 2010	CITS	USA	Indianapolis Violence Reduction Partnership	Indicated, focused deterrence	TAU	5–24, M = NI	NR	24	NR	NR	NR	NR	Homicide (register data)	NR
Papachristos, 2007	CITS	USA	Project Safe Neighborhoods	Indicated, focused deterrence	TAU	NR	NR	72	NR	NR	NR	NR	Homicide (register data)	NR
Author, year	Design	Context	Intervention	Type of intervention	Comparision	Age range (year), Mean age	Males (%)	Follow-up (months)	Exp_N	Cont_N	Exp_N at follow-up	Control N_at follow-up	Primary outcome	Secondary outcome
Corsaro & Brunson, 2013	CITS	USA	Drug market intervention	Indicated, drug markets	Other crime types	NR	NR	14	NR	NR	NR	NR	Violent offenses (register data)	Drug and disorder crimes (register data)
Corsaro et al., 2013	CITS	USA	Drug market intervention	Indicated, drug markets	TAU	NR	NR	14	NR	NR	NR	NR	Aggregated violent offenses (register data)	NR
Corsaro et al., 2010	CITS	USA	Drug market intervention	Indicated, drug markets	TAU	NR	NR	24	NR	NR	NR	NR	Aggregated violent offenses (register data)	Drug crimes (register data)
Saunders et al., 2015	CITS	USA	Drug market intervention	Indicated, drug markets	TAU	NR	NR	24	NR	NR	NR	NR	Violent crimes (register data)	Drug crimes (register data)
Saunders et al., 2015	CITS	USA	Drug market intervention	Indicated, drug markets	TAU	NR	NR	12	NR	NR	NR	NR	Violent crimes (register data)	Drug crimes (register data)
Park et al., 2021	NRSI	USA	Gang Reduction Youth Development Incident Response Program	Indicated, mediation	TAU	NR	NI	48	NR	NR	NR	NR	Violent retaliation crimes (register data)	NR
Fox et al. 2015	NRSI	USA	Phoenix TRUCE Project	Indicated mediation	TAU	16–25, M = NI	73	19	NR	NR	NR	NR	Shooting (register data)	NR
Wilson & Chermak, 2011	CITS	USA	One Vision One Life	Indicated, mediation	TAU	15–24, M = NI	NI	44	NR	NR	NR	NR	Homicides (register data)	NR
Buggs et al., 2022	CITS	USA	Cure Violence/Safe Streets	Indicated, mediation	TAU	15–34, M = NI	42–50	36	NR	NR	NR	NR	Homicides (register data)	NR
Corburn et al., 2022	CITS	USA	Advance Peace	Indicated, mediation	TAU	NI	NI	18	NR	NR	NR	NR	Gun homicides (register data)	NR
Boots et al., 2018	NRSI	USA	SWIFT Court program	Indicated, probation	TAU	17–25, M = 19.8	96	24	72	108	72	108	Arrests (register data)	NR
Cook et al., 2015	RCT	USA	Safe Street Prisoner Release Initiative	Indicated, prison and probation	TAU	0–35, M = 28.3	NI	12	106	130	106	130	Arrest (register data)	NR
Di Placido et al., 2006	NRSI	Canada	High intensity cognitive–behavioral programs	Indicated, prison	TAU	NI, M = 23.7	100	24	40	40	36	34	Recidivism (register data)	NR
Spooner et al., 2017	NRSI	USA	GitRedy	Indicated, prison	TAU	NI, M = 17	96	48	437	179	437	179	Arrest rate (register data)	NR
Weinrath et al., 2016	NRSI	Canada	Spotlight Serious Offender Services Unit	Indicated, probation	TAU	12–19, M = 15.5	100	12	57	85	57	85	Court convictions (register data)	NR
Lane et al., 2007	RCT	USA	South Oxnard Challenge Project	Indicated, probation	TAU	12–18, M = 17.5	79	12	264	275	151	163	Violent crimes (self-reported)	NR
Braga et al., 2009	NRSI	USA	Boston Reentry Initiative	Indicated, prison and probation	TAU	18–32, M = 21.7	100	36	108	309	208	309	Violent crimes (register data)	NR
Williams et al., 2014*	NRSI	Scotland	Community Initiative to Reduce Violence	Indicated, street workers, community	TAU	16–29, M = 17.8	100	24	167	167	124	124	Physical violence (register data)	NR
Matthay et al., 2019*	CITS	USA	Operation Peacemaker Fellowship	Indicated, fellowship, mentorship, social services	TAU	NI	100	66	NR	NR	NR	NR	Firearm violence (register data)	NR
Koper et al., 2016*	CITS	USA	Police-Led Community Initiative to Reduce Gun Violence	Indicated, police-community partnership	TAU	NR	NR	9	NR	NR	NR	NR	Gun violence (register data)	NR

	Intervention	Outcome	Subjects; studies	Effect size (95% CI)	Grade-based certainty of evidence
Universal prevention	School-based programs	Gang membership (self-report)	n = 8.808 (2 RCT, 1 NRSI)	Positive effect on gang membership	Low certainty of evidence (⊕⊕○○	−1.5 Risk of bias^a –0.5 Indirectness^b
Selective prevention	Family-based therapy	Gang membership (self-report)	n = 264 (1 RCT, 1 NRSI)	Not possible to determine	Very low certainty of evidence (⊕○○○)	−1.5 Risk for bias^c −2 Imprecision^d
Indicated prevention	Focused deterrence	Firearm violence (registry data)	n = NR (13 CITS)	IRR = 0.74 (95% CI, 0.67–0.81).	Moderate certainty of evidence (⊕⊕⊕○)	–1 Publication bias^e
Indicated prevention	Drug market intervention	Firearm violence (registry data)	n = NR (5 CITS)	IRR = 0.98 (95% CI, 0.81–1.15)	Very low certainty of evidence (⊕○○○)	–2 Risk of bias^f –1 Imprecision^g
Indicated prevention	Drug market intervention	Drug crime (registry data)	n = NR (4 CITS)	IRR = 0.65 (95% CI, 0.43–0.88).	Low certainty of evidence (⊕⊕○○)	–2 Risk for bias^f
Indicated prevention	Outreach programs to enhance mediation	Firearm violence (registry data)	n = NR (2 NRSI, 3 CITS)	Not possible to determine	Very low certainty of evidence (⊕○○○)	−1 Risk for bias^h −2 Heterogeneityⁱ
Indicated prevention	Correctional services in prison	Crime recidivism (registry data)	n = 693 (2 NRSI)	OR = 0.59 (95% CI, 0.16–2.16)	Very low certainty of evidence (⊕○○○)	−1 Risk for bias^j −2 imprecision^k
Indicated prevention	Correctional services on parole	Crime recidivism (registry data)	n = 1.678 (5 NRSI, 2 RCT)	OR = 0.56 (95% CI, 0.41–0.76)	Low certainty of evidence (⊕⊕○○)	−1 Risk for bias^l −1 Indirectness^m

Footnotes

Author Note

This synthesis was registered on September 30, 2022, with the International Prospective Register of Systematic Reviews, CRD42,22360672, and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

This article is adapted from a systematic review carried out by the Swedish Agency for Health Technology Assessment and Assessment of Social Services which provided funding for the study (SBU, 2023).

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by the Swedish Agency for Health Technology Assessment and Assessment of Social Services

ORCID iD

Caroline Mellgren

References

Alonso-Coello

Schünemann

H. J.

Moberg

Brignardello-Petersen

Akl

E. A.

Davoli

Treweek

Mustafa

R. A.

Rada

Rosenbaum

Morelli

Guyatt

G. H.

Oxman

A. D.

(2016). GRADE Evidence to decision (EtD) frameworks: A systematic and transparent approach to making well informed healthcare choices. 1: Introduction. BMJ, 353, i2016. https://doi.org/10.1136/bmj.i2016

Ashworth

Zedner

(2014). Preventive justice (1 ed.). Oxford University Press.

Barnes

J. C.

Beaver

K. M.

Miller

J. M.

(2010). Estimating the effect of gang membership on nonviolent and violent delinquency: A counterfactual analysis. Aggressive Behavior, 36(6), 437–451. https://doi.org/10.1002/ab.20359

Boots

D. P.

Wareham

Stevens-Martin

Barbieri

(2018). A preliminary evaluation of the supervision with immediate enforcement probation program for adult gang–affiliated offenders in Texas. Criminal Justice and Behavior, 45(7), 1047–1070. https://doi.org/10.1177/0093854818774386

Braga

Anthony A

(2008). Pulling levers focused deterrence strategies and the prevention of gun homicide. Journal of Criminal Justice, 36(4), 332–343. http://doi.org/10.1016/j.jcrimjus.2008.06.009

Braga

Anthony A

(2016). The continued importance of measuring potentially harmful impacts of crime prevention programs: the academy of experimental criminology 2014 Joan McCord lecture. Journal of Experimental Criminology, 12(1), 1–20. http://doi.org/10.1007/s11292-016-9252-4

Braga

Anthony A

Hureau

David M.

Papachristos

Andrew V

(2014). Deterring gang-involved gun violence: Measuring the impact of Boston’s operation ceasefire on street gang behavior. Journal of Quantitative Criminology, 30(1), 113–139. http://doi.org/10.1007/s10940-013-9198-x

Braga

Anthohy A

Kennedy

David M.

Waring

Elin J

Piehl

Anne Morrison

(2001). Problem-oriented policing, deterrence, and youth violence: An evaluation of Boston's operation ceasefire. Journal of Research in Crime and Delinquency, 38(3), 195–225. http://doi.org/10.1177/0022427801038003001

Braga

A. A.

Piehl

A. M.

Hureau

(2009). Controlling violent offenders released to the community: An evaluation of the Boston reentry initiative. Journal of Research in Crime and Delinquency, 46(4), 411–436. https://doi.org/10.1177/0022427809341935

10.

Braga

Anthony A

Pierce

Glenn L.

McDevitt

Jack

Bond

Brenda J

Cronin

Shea

(2008). The strategic prevention of gun violence among gang‐involved offenders. Justice Quarterly, 25(1), 132–162. https://doi.org/10.1080/07418820801954613

11.

Braga

A. A.

Turchan

B. S.

Papachristos

A. V.

Hureau

D. M.

(2019). Hot spots policing and crime reduction: An update of an ongoing systematic review and meta-analysis. Journal of Experimental Criminology, 15(3), 289–311. https://doi.org/10.1007/s11292-019-09372-3

12.

Braga

A. A.

Weisburd

D. L.

(2012). The effects of “pulling levers” focused deterrence strategies on crime. Campbell Systematic Reviews, 8(1), 1–90. https://doi.org/10.4073/csr.2012.6

13.

Braga

A. A.

Weisburd

Turchan

(2018). Focused deterrence strategies and crime control. Criminology & Public Policy, 17(1), 205–250. https://doi.org/10.1111/1745-9133.12353

14.

Brantingham

P. Jeffrey

Tita

George

Herz

Denise

(2021). The impact of the City of Los Angeles mayor’s office of gang reduction and youth development (GRYD) comprehensive strategy on crime in the City of Los Angeles. Justice Evaluation Journal, 4(2), 217–236. http://doi.org/10.1080/24751979.2021.1887709

15.

Brinchmann

Widding-Havneraas

Modini

Rinaldi

Moe

C. F.

McDaid

Park

A. L.

Killackey

Harvey

S. B.

Mykletun

(2020). A meta-regression of the impact of policy on the efficacy of individual placement and support. Acta Psychiatrica Scandinavica, 141(3), 206–220. https://doi.org/10.1111/acps.13129

16.

Buggs

S. A.

Webster

D. W.

Crifasi

C. K.

(2022). Using synthetic control methodology to estimate effects of a cure violence intervention in Baltimore, Maryland. Injury Prevention, 28(1), 61–67. https://doi.org/10.1136/injuryprev-2020-044056

17.

Circo

Giovanni M

Krupa

Julie M.

McGarrell

Edmund

De Biasi

Alaina

(2021). Focused deterrence and program fidelity: Evaluating the impact of Detroit ceasefire. Justice Evaluation Journal, 4(1), 112–130. http://doi.org/10.1080/24751979.2020.1827938

18.

Clark-Moorman

Kyleigh

Rydberg

Jason

McGarrell

Edmund F

(2019). Impact evaluation of a parolee-based focused deterrence program on community-level violence. Criminal Justice Policy Review, 30(9), 1408–1430. http://doi.org/10.1177/0887403418812999

19.

Committee on Developing Evidence-Based Standards for Psychosocial Interventions for Mental, D., Board on Health Sciences, P., & Institute of, M (2015). The national academies collection: Reports funded by National Institutes of Health. In M. J. England, A. S. Butler, & M. L. Gonzalez (Eds.), Psychosocial interventions for mental and substance use disorders: A framework for establishing evidence-based standards. National Academies Press. https://doi.org/10.17226/19013.

20.

Cook

P. J.

Kang

Braga

A. A.

Ludwig

O’Brien

M. E.

(2015). An experimental evaluation of a comprehensive employment-oriented prisoner re-entry program. Journal of Quantitative Criminology, 31(3), 355–382. https://doi.org/10.1007/s10940-014-9242-5

21.

Cook

Philip, J.

Kang

Songman

Braga

Anthony A.

Ludwig

Jens

O’Brien

Mallory E

. (2015). An experimental evaluation of a comprehensive employment-oriented prisoner re-entry program. Journal of Quantitative Criminology, 31(3), 355–382. httsp://doi.org/10.1007/s10940-014-9242-5

22.

Corburn

Nidam

Fukutome-Lopez

(2022). The art and science of urban gun violence reduction: Evidence from the advance peace program in sacramento, California. Urban Science, 6(1), 6. https://www.mdpi.com/2413-8851/6/1/6. https://doi.org/10.3390/urbansci6010006

23.

Corsaro

Brunson

R. K.

(2013). Are suppression and deterrence mechanisms enough? Examining the “pulling levers” drug market intervention strategy in Peoria, Illinois, USA. International Journal of Drug Policy, 24(2), 115–121. https://doi.org/10.1016/j.drugpo.2012.12.006

24.

Corsaro

Brunson

R. K.

McGarrell

E. F.

(2010). Evaluating a policing strategy intended to disrupt an illicit street-level drug market. Evaluation Review, 34(6), 513–548. https://doi.org/10.1177/0193841X10389136

25.

Corsaro

Brunson

R. K.

McGarrell

E. F.

(2013). Problem-oriented policing and open-air drug markets. Crime & Delinquency, 59(7), 1085–1107. https://doi.org/10.1177/0011128709345955

26.

Curry

G. D.

Decker

S. H.

Egley

(2002). Gang involvement and delinquency in a middle school population. Justice Quarterly, 19(2), 275–292. https://doi.org/10.1080/07418820200095241

27.

DeLisi

Barnes

J. C.

Beaver

K. M.

Gibson

C. L.

(2009). Delinquent gangs and adolescent victimization revisited: A propensity score matching approach. Criminal Justice and Behavior, 36(8), 808–823. https://doi.org/10.1177/0093854809337703

28.

Densley

James A

Adler

Joanna R.

Zhu

Lijun

Lambine

Mackenzie

(2017). Growing against gangs and violence: Findings from a process and outcome evaluation. Psychology of Violence, 7(2), 242–252. https://doi.org/10.1037/vio0000054

29.

Di Placido

Simon

T. L.

Witte

T. D.

Wong

S. C.

(2006). Treatment of gang members can reduce recidivism and institutional misconduct. Law and Human Behavior, 30(1), 93–114. https://doi.org/10.1007/s10979-006-9003-6

30.

Engel

Robin S

Tillyer

Marie Skubak

Corsaro

Nicholas

(2013). Reducing gang violence using focused deterrence: Evaluating the Cincinnati initiative to reduce violence (CIRV). Justice Quarterly, 30(3), 403–439. httsp://doi.org/10.1080/07418825.2011.619559

31.

Esbensen

F. A.

Osgood

D. W.

Peterson

Taylor

T. J.

Carson

D. C.

(2013). Short- and long-term outcome results from a multisite evaluation of the G.R.E.A.T. Program. Criminology & Public Policy, 12(3), 375–411. https://doi.org/10.1111/1745-9133.12048

32.

Esbensen

F. A.

Osgood

D. W.

Taylor

T. J.

Peterson

Freng

(2001). How great is G.R.E.A.T.? Results from a longitudinal quasi-experimental design*. Criminology & Public Policy, 1(1), 87–118. https://doi.org/10.1111/j.1745-9133.2001.tb00078.x

33.

Europol (2024). Decoding the EU’s most threatening criminal networks. Publications Office of the European Union. https://www.europol.europa.eu/cms/sites/default/files/documents/Europol%20report%20on%20Decoding%20the%20EU-s%20most%20threatening%20criminal%20networks.pdf .

34.

Ferzan

K. K.

(2014). Preventive justice and the presumption of innocence. Criminal law and Philosophy, 8(2), 505–525. https://doi.org/10.1007/s11572-013-9275-0

35.

Fisher

Gardner

F. E.

Montgomery

(2008). Cognitive-behavioural interventions for preventing youth gang involvement for children and young people (7-16). The Cochrane Database of Systematic Reviews, 2008(2), CD007008. https://doi.org/10.1002/14651858.CD007008.pub2

36.

Fisher

Montgomery

Gardner

F. E.

(2008). Opportunities provision for preventing youth gang involvement for children and young people (7-16). The Cochrane Database of Systematic Reviews, 2008(2), CD007002. https://doi.org/10.1002/14651858.CD007002.pub2

37.

Fox

Bryanna

Allen

Scott F

Toth

Alexander

(2022). Evaluating the impact of Project Safe Neighborhoods (PSN) initiative on violence and gun crime in Tampa: does it work and does it last?. Journal of Experimental Criminology, 18(3), 543–567. https://doi.org/10.1007/s11292-021-09461-2

38.

Fox

A. M.

Katz

C. M.

Choate

D. E.

Hedberg

E. C.

(2014). Evaluation of the Phoenix TRUCE project: A replication of Chicago CeaseFire. Justice Quarterly, 32(1), 85–115. https://doi.org/10.1080/07418825.2014.902092

39.

Gebo

Erika

Bond

Brenda J

(2022). Advancing interorganizational crime and violence reduction goals through a relational change intervention. Criminal Justice Policy Review, 33(5), 455–479. http://doi.org/10.1177/08874034211065996

40.

Gerell

Rostami

Sturup

Mellgren

Sundell

Johansson

Dagerhamn

Jonsson

A. K.

Fundell

Tranæus

(2022). Interventions to prevent or reduce gang-related crime among children and young adults (PROSPERO 2022 CRD42022360672). https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022360672

41.

Grunwald

Papachristos

A.V.

(2017). Project safe neighborhoods in Chicago: Looking back a decade later. Journal of Criminal Law and Criminology, 107(1), 131–160.

42.

Guyatt

G. H.

Oxman

A. D.

Vist

G. E.

Kunz

Falck-Ytter

Alonso-Coello

Schunemann

H. J.

(2008). GRADE: An emerging consensus on rating quality of evidence and strength of recommendations. BMJ, 336(7650), 924–926. https://doi.org/10.1136/bmj.39489.470347.AD

43.

Hardy

(2017). Preventive justice principles for countering violent extremism. In Tulich

Ananian-Welch

Bronitt

Murray

(Eds.), Regulating preventive justice: Principle, policy and paradox (1st ed., pp. 117–135). Routledge.

44.

Hawkins

J. David

Catalano

Richard F

Arthur

Michael W.

Egan

Elizabeth

Brown

Eric C

Abbott

Robert D.

Murray

David M

(2008). Testing communities that care: The rationale, design and behavioral baseline equivalence of the community youth development study. Prevention Science, 9(3), 178–190. http://doi.org/10.1007/s11121-008-0092-y

45.

Higgins

J. P. T.

Thomas

Chandler

Cumpston

Page

M. J.

Welch

V. A.

(2021). Cochrane handbook for systematic reviews of interventions version 6.2 (updated February 2021). The Cochrane Collaboration. https://training.cochrane.org/handbook .

46.

Higginson

Benier

Shenderovich

Bedford

Mazerolle

Murray

(2015). Preventive interventions to reduce youth involvement in gangs and gang crime in low- and middle-income countries: A systematic review. Campbell Systematic Reviews, 11(1), 1–176. https://doi.org/10.4073/csr.2015.18

47.

Hodgkinson

Marshall

Berry

Newman

Reynolds

Burton

Dickson

Anderson

(2009). Reducing gang related crime: A systematic review of ‘comprehensive’ interventions. EPPI-Centre, Social Science Research Unit, Institute of Education, University of London, EPPI-Centre report no: 1704. https://eppi.ioe.ac.uk/cms/Default.aspx?tabid=2444.

48.

Ioannidis

J. P. A.

Tarone

McLaughlin

J. K.

(2011). The false-positive to false-negative ratio in epidemiologic studies. Epidemiology, 22(4), 450–456. https://doi.org/10.1097/EDE.0b013e31821b506e

49.

Jeffries

Sara R

Myers

David L.

Kringen

Jonathan Allen

Schack

Ron

(2019). Evaluating project safe neighborhoods in connecticut: A youth opportunity initiative. Crime Prevention and Community Safety, 21(4), 325–345. https://doi.org/10.1057/s41300-019-00076-4

50.

Kennedy

D. M.

(2006). Advocate old wine in new bottles: Policing and the lessons of pulling levers. In Braga

A. A.

Weisburd

(Eds.), Police innovation: Contrasting perspectives (pp. 155–170). Cambridge University Press. https://doi.org/10.1017/CBO9780511489334.008

51.

Kitzman

Olds

D. L.

Knudtson

M. D.

Cole

Anson

Smith

J. A.

Fishbein

DiClemente

Wingood

Caliendo

A. M.

Hopfer

Miller

Conti

(2019). Prenatal and infancy nurse home visiting and 18-year outcomes of a randomized trial. Pediatrics, 144(6), 82–94. https://doi.org/10.1542/peds.2018-3876

52.

Kochel

T. R

Nouri

Seyvan

Samadi

S. Yaser

(2022). Impact of focused deterrence on lived experiences with gangs and gun violence: Extending effects beyond officially recorded crime. Criminal Justice Policy Review, 33(5), 507–535. https://doi.org/10.1177/08874034211063812

53.

Koper

C. S.

Woods

D. J.

Isom

(2016). Evaluating a police-led community initiative to reduce gun violence in St. Louis. Police Quarterly, 19(2), 115–149. https://doi.org/10.1177/1098611115608506

54.

Krohn

M. D.

Thornberry

T. P.

(2008). Longitudinal perspectives on adolescent street gangs. In Liberman

A. M.

(Ed.), The long view of crime: A synthesis of longitudinal research (pp. 128–160). Springer New York. https://doi.org/10.1007/978-0-387-71165-2_4

55.

Lane

Meeker

J. W.

(2000). Subcultural diversity and the fear of crime and gangs. Crime & Delinquency, 46(4), 497–521. https://doi.org/10.1177/0011128700046004005

56.

Lane

Turner

Fain

Sehgal

(2007). The effects of an experimental intensive juvenile probation program on self-reported delinquency and drug use. Journal of Experimental Criminology, 3(3), 201–219. https://doi.org/10.1007/s11292-007-9038-9

57.

Lippert-Rasmussen

(2022). Why ‘indirect discrimination’ is a useful legal but not a useful moral concept. Erasmus Journal for Philosophy and Economics, 15(1), 83–107. https://doi.org/10.23941/ejpe.v15i1.655

58.

Lopez Bernal

Cummins

Gasparrini

(2018). The use of controls in interrupted time series studies of public health interventions. International Journal of Epidemiology, 47(6), 2082–2093. https://doi.org/10.1093/ije/dyy135

59.

Lopez Bernal

Cummins

Gasparrini

(2019). Difference in difference, controlled interrupted time series and synthetic controls. International Journal of Epidemiology, 48(6), 2062–2063. https://doi.org/10.1093/ije/dyz050

60.

Mallion

J. S.

Wood

J. L.

(2020). Good lives model and street gang membership: A review and application. Aggression and Violent Behavior, 52, 101393. https://doi.org/10.1016/j.avb.2020.101393

61.

Marshall

I. J.

L'Esperance

Marshall

Thomas

Noel-Storr

Soboczenski

Nye

Nenkova

Wallace

B. C.

(2021). State of the evidence: A survey of global disparities in clinical trials. BMJ global health, 6(1). e004145. https://doi.org/10.1136/bmjgh-2020-004145

62.

Matthay

E. C.

Farkas

Rudolph

K. E.

Zimmerman

Barragan

Goin

D. E.

Ahern

(2019). Firearm and nonfirearm violence after operation peacemaker fellowship in Richmond, California, 1996-2016. American Journal of Public Health, 109(11), 1605–1611. https://doi.org/10.2105/AJPH.2019.305288

63.

McGarrell

Edmund F

Corsaro

Nicholas

Hipple

Natalie Kroovand

Bynum

Timothy S.

(2010). Project safe neighborhoods and violent crime trends in US cities: Assessing violent crime impact. Journal of Quantitative Criminology, 26(2), 165–190. https://doi.org/10.1007/s10940-010-9091-9

64.

McGarrell

Edmund F

Corsaro

Nicholas

Melde

Chris

Hipple

Natalie K.

Bynum

Timothy

Cobbina

Jennifer

(2013). Attempting to reduce firearms violence through a Comprehensive Anti-Gang Initiative (CAGI): An evaluation of process and impact. Journal of Criminal Justice, 41(1), 33–43. https://doi.org/10.1016/j.jcrimjus.2012.11.001

65.

McKenzie

J. E.

Brennan

S. E.

(2023). Chapter 12: Synthesizing and presenting findings using other methods. In Higgins

J. P. T.

Thomas

Chandler

Cumpston

Page

M. J.

Welch

V. A.

(Eds.), Cochrane Handbook for Systematic Reviews of Interventions version 6.4. Cochrane. www.training.cochrane.org/handbook .

66.

Munthe

(2011). The price of precaution and the ethics of risk. Springer.

67.

National Network for Safe Communities (2015). Drug market intervention: An implementation guide. Office of Community Oriented Policing Services. https://portal.cops.usdoj.gov/resourcecenter/RIC/Publications/cops-p303-pub.pdf

68.

Nieri

Apkarian

Kulis

Marsiglia

F. F.

(2015). Effects of a youth substance use prevention program on stealing, fighting, and weapon use. The Journal of Primary Prevention, 36(1), 41–49. https://doi.org/10.1007/s10935-014-0373-0

69.

Page

M. J.

McKenzie

J. E.

Bossuyt

P. M.

Boutron

Hoffmann

T. C.

Mulrow

C. D.

Shamseer

Tetzlaff

J. M.

Akl

E. A.

Brennan

S. E.

Chou

Glanville

Grimshaw

J. M.

Hróbjartsson

Lalu

M. M.

Loder

E. W.

Mayo-Wilson

McDonald

Moher

(2021). The PRISMA 2020 statement: An updated guideline for reporting systematic reviews. BMJ, 372, n71. https://doi.org/10.1136/bmj.n71

70.

Papachristos

Andrew V

Kirk

David S.

(2015). Changing the street dynamic. Criminology & Public Policy, 14(3), 525–558. https://doi.org/10.1111/capp.2015.14.issue-3

71.

Park

Schoenberg

F. P.

Bertozzi

A. L.

Brantingham

P. J.

(2021). Investigating clustering and violence interruption in gang-related violent crime data using spatial–temporal point processes with ovariates. Journal of the American Statistical Association, 116(536), 1674–1687. https://doi.org/10.1080/01621459.2021.1898408

72.

Penfold

R. B.

Zhang

(2013). Use of interrupted time series analysis in evaluating health care quality improvements. Academic Pediatrics, 13(6 Suppl), S38–S44. https://doi.org/10.1016/j.acap.2013.08.002

73.

Petrosino

Turpin-Petrosino

Hollis-Peel

M. E.

Lavenberg

J. G.

(2013). ‘Scared straight’ and other juvenile awareness programs for preventing juvenile delinquency. The Cochrane Database of Systematic Reviews, 2013(4), CD002796. https://doi.org/10.1002/14651858.CD002796.pub2

74.

Phalen

Peter

Bridgeford

Erricka

Gant

Letrice

Kivisto

Aaron

Ray

Brad

Fitzgerald

Simon

(2020). Baltimore Ceasefire 365: Estimated impact of a recurring community-led ceasefire on gun violence. American Journal of Public Health, 110(4), 554–559. https://doi.org/10.2105/AJPH.2019.305513

75.

Piehl

Anne Morrison

Cooper

Suzanne J

Braga

Anthony A.

Kennedy

David M

(2003). Testing for structural breaks in the evaluation of programs. Review of Economics and Statistics, 85(3), 550–558. https://doi.org/10.1162/003465303322369713

76.

Ramsey

A. L.

Rust

J. O.

Sobel

S. M.

(2003). Evaluation of the gang resistance and training (GREAT) program: A school-based prevention program. Education, 124(2), 297–309. https://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=11978670&site=ehost-live

77.

Roks

R. A.

Densley

J. A.

(2019). From breakers to bikers: The evolution of the Dutch crips ‘gang’. Deviant Behavior, 41(4), 525–542. https://doi.org/10.1080/01639625.2019.1572301

78.

Roman

Caterina G

Forney

Megan

Hyatt

Jordan M.

Klein

Hannah J

Link

Nathan W.

(2020). Law enforcement activities of Philadelphia’s group violence intervention: An examination of arrest, case processing, and probation levers. Police Quarterly, 23(2), 232–261. https://doi.org/10.1177/1098611119895069

79.

Roman

Caterina G

Link

Nathan W.

Hyatt

Jordan M

Bhati

Avinash

Forney

Megan

(2019). Assessing the gang-level and community-level effects of the Philadelphia Focused Deterrence strategy. Journal of Experimental Criminology, 15(4), 499–527. https://doi.org/10.1007/s11292-018-9333-7

80.

Rostami

(2017). Street-gang violence in Sweden is a growing concern. Sociologisk Forskning, 54(4), 365–368. https://doi.org/10.37062/sf.54.18237

81.

Rowhani-Rahbar

Oesterle

Gause

E. L.

Kuklinski

M. R.

Ellyson

A. M.

Schleimer

J. P.

Dalve

Weybright

E. H.

Briney

J. S.

Hawkins

J. D.

(2023). Effect of the communities that care prevention system on adolescent handgun carrying: A cluster-randomized clinical trial. JAMA Network Open, 6(4), e236699. https://doi.org/10.1001/jamanetworkopen.2023.6699

82.

Saunders

Lundberg

Braga

A. A.

Ridgeway

Miles

(2015). A synthetic control approach to evaluating place-based crime interventions. Journal of Quantitative Criminology, 31(3), 413–434. https://doi.org/10.1007/s10940-014-9226-5

83.

Saunders

Robbins

Ober

A. J.

(2017). Moving from efficacy to effectiveness. Criminology & Public Policy, 16(3), 787–814. https://doi.org/10.1111/1745-9133.12316

84.

SBU (2023). Psykosociala insatser för att förebygga och minska gängkriminalitet bland barn och unga vuxna (SBU Utvärderar 369). https://SBU.se/en.

85.

Shadish

W. R.

Cook

T. D.

Campbell

D. T.

(2001). Quasi-experimentation: Interrupted time series designs. In Experimental and quasi-experimental designs for generalized causal inference (2 ed., pp. 179ff). Houghton Mifflin Boston.

86.

Shi

Lin

(2019). The trim-and-fill method for publication bias: Practical guidelines and recommendations based on a large database of meta-analyses. Medicine, 98(23), e15987. https://doi.org/10.1097/MD.0000000000015987

87.

Spooner

Pyrooz

D. C.

Webb

V. J.

Fox

K. A.

(2017). Recidivism among juveniles in a multi-component gang reentry program: Findings from a program evaluation in Harris County, Texas. Journal of Experimental Criminology, 13(2), 275–285. https://doi.org/10.1007/s11292-017-9288-0

88.

Stacey

Tulich

Ananian-Welch

Bronitt

Murray

(2017). Preventive justice, the precautionary principle and the rule of law. In Regulating preventive justice: Principle, policy and paradox (1 ed., pp. 23–39). Routledge.

89.

Tapia

Posadas

C. E.

(2017). Revisiting the comprehensive gang intervention model: Implementation, data, and program impact in a chronic gang site. Journal of Gang Research, 24(3), 1–16.

90.

Thornberry

T. P.

Kearley

Gottfredson

D. C.

Slothower

M. P.

Devlin

D. N.

Fader

J. J.

(2018). Reducing crime among youth at risk for gang involvement. Criminology & Public Policy, 17(4), 953–989. https://doi.org/10.1111/1745-9133.12395

91.

Thornberry

Terence P

Kearley

Brook

Gottfredson

Denise C.

Slothower

Molly P

Devlin

Deanna N.

Fader

Jamie J

(2018). Reducing crime among youth at risk for gang involvement. Criminology & Public Policy, 17(4), 953–989. http://doi.org/10.1111/capp.2018.17.issue-4

92.

Trulson

Triplett

Snell

(2001). Social control in a school setting: Evaluating a school-based boot camp. Crime & Delinquency, 47(4), 573–609. https://doi.org/10.1177/0011128701047004005

93.

Uchida

Craig D

Swatt

Marc

Schnobrich-Davis

Julie

Connor

Christine

Shutinya

Mariel

Wagner

Daniel

(2019). A randomized control trial of a targeted high-risk offender program across three jurisdictions. Police Quarterly, 22(2), 192–216. https://doi.org/10.1177/1098611118807771

94.

UN (1989). Convention on the rights of the child (General Assembly resolution 44/25). Unicef. https://www.unicef.org/child-rights-convention/convention-text.

95.

Valdez

Cepeda

Parrish

Horowitz

Kaplan

(2013). An adapted brief strategic family therapy for gang-affiliated Mexican American adolescents. Research on Social Work Practice, 23(4), 383–396. https://doi.org/10.1177/1049731513481389

96.

van der Pol

T. M.

van Domburgh

van Widenfelt

B. M.

Hurlburt

M. S.

Garland

A. F.

Vermeiren

R. R. J. M.

(2019). Common elements of evidence-based systemic treatments for adolescents with disruptive behaviour problems. The Lancet Psychiatry, 6(10), 862–868. https://doi.org/10.1016/S2215-0366(19)30085-9

97.

Wallace

Danielle

Papachristos

Andrew V

Meares

Tracey

Fagan

Jeffrey

(2016). Desistance and legitimacy: The impact of offender notification meetings on recidivism among high risk offenders. Justice Quarterly, 33(7), 1237–1264. https://doi.org/10.1080/07418825.2015.1081262

98.

Weerman

Maxson

Esbensen

F.-A.

Aldridge

Medina

Gemert

(2009). Eurogans program manual. Background, development, and use of the Eurogang instruments in multi-site, multi-method comparative research. University of Missouri-St. Louis. https://www.umsl.edu/ccj/research/eurogang-project.html .

99.

Weinrath

Donatelli

Murchison

M. J.

(2016). Mentorship: A missing piece to manage juvenile intensive supervision programs and youth gangs? Canadian Journal of Criminology and Criminal Justice, 58(3), 291–321. https://doi.org/10.3138/cjccj.2015.E19

100.

Welsh

B. C.

Rocque

(2014). When crime prevention harms: A review of systematic reviews. Journal of Experimental Criminology, 10(3), 245–266. https://doi.org/10.1007/s11292-014-9199-2

101.

Werb

Rowell

Guyatt

Kerr

Montaner

Wood

(2011). Effect of drug law enforcement on drug market violence: A systematic review. International Journal of Drug Policy, 22(2), 87–94. https://doi.org/10.1016/j.drugpo.2011.02.002

102.

WHO (2023). Youth violence. World Health Organization (WHO). https://www.who.int/news-room/fact-sheets/detail/youth-violence .

103.

Williams

D. J.

Currie

Linden

Donnelly

P. D.

(2014). Addressing gang-related violence in Glasgow: A preliminary pragmatic quasi-experimental evaluation of the community initiative to reduce violence (CIRV). Aggression and Violent Behavior, 19(6), 686–691. https://doi.org/10.1016/j.avb.2014.09.011

104.

Wilson

D. B.

(2022). The relative incident rate ratio effect size for count-based impact evaluations: When an odds ratio is not an odds ratio. Journal of Quantitative Criminology, 38(2), 323–341. https://doi.org/10.1007/s10940-021-09494-w

105.

Wilson

J. M.

Chermak

(2011). Community-driven violence reduction programs. Criminology & Public Policy, 10(4), 993–1027. https://doi.org/10.1111/j.1745-9133.2011.00763.x

106.

Wong

Gravel

Bouchard

Morselli

Descormiers

(2012). Effectiveness of street gang control strategies: A systematic review and meta-analysis of evaluation studies . Public Safety Canada, 2–76. https://doi.org/10.13140/RG.2.1.1314.4086.

107.

Wong

J. S.

Wood

J. L.

Gravel

Bouchard

Descormiers

Morselli

(2016). Promises kept? A meta-analysis of gang membership prevention programs. Journal of Criminological Research, Policy and Practice, 2(2), 134–147. https://doi.org/10.1108/jcrpp-06-2015-0018

Psychosocial Interventions Preventing Gang-Related Crime Among Young People: A Systematic Review

Abstract

Keywords

Method

Eligibility Criteria

Type of Literature and Country of Origin

Target Population

Interventions

Outcome

Study Design

Literature Search Strategy

Risk of Bias Assessment and Data Extraction

Grading of Evidence

Statistical Procedure for Meta-Analysis

Synthesis Without Meta-Analysis (SWiM)

Publication Bias

Results

Synthesis on Universal Interventions

Synthesis on Selective Interventions

Synthesis on Indicated Interventions

Focused Deterrence

Drug Market Intervention (DMI)

Outreach Programs to Enhance Mediation

Correctional Services

Additional Single Study Results

Discussion and Applications to Practice

Footnotes

Author Note

Declaration of Conflicting Interests

Funding

ORCID iD

References