BACKGROUND: Despite evidence of efficacy, a substantial percentage of children with attention deficit hyperactivity disorder (ADHD) either do not begin medication prescribed for their core symptoms or fail to continue treatment. OBJECTIVE: The purpose of this study was to understand (a) how parents decide to use medication to treat their child’s ADHD and (b) the factors that influence their adherence to medication over time. DESIGN: Grounded theory guided data collection and analysis. Sixteen semistructured interviews with parents (13 mothers, 3 fathers) of children with ADHD were conducted. RESULTS: The substantive theory developed from the data demonstrates that in seeking to help their child and restore a sense of stability around family life, parents engage in a process of “doing what helps most” in deciding to use medication to treat their child’s ADHD. CONCLUSIONS: Interventions to support and guide parents throughout the decisional process are critical to meet the needs of families of children with ADHD.