This article offers the first systematic analysis of cross-generational and cross-organizational aspects of jihadist foreign fighter (JFF) mobilization. How are individuals fighting in Syria different from foreign fighters who fought in the previous jihadist wars? What factors distinguish the Islamic State (IS) fighters from individuals joining other jihadist groups in Syria? The article builds an original sample of 477 JFFs from Turkey spanning three decades and employs the Random Forest technique, a method with several distinct advantages over regression analysis in the study of small N conflict data. The results have substantial and practical implications and show that fighters in Syria and IS fighters have different demographic characteristics and life experiences than fighters in pre-Syria wars and non-IS fighters in Syria, respectively. They inform more empirically grounded theory building about the recruitment motives and methods of JFFs.
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