How do rebel organizations capitalize on transit migration? While numerous studies have examined the role of refugees, this article explores a broader yet significant category of mobile populations in civil conflict. Focusing on Mali, I argue that transit migration increases rebel capacity based on three causal mechanisms: Obstacles in transit, camping banditry, and dynamic recruitment. Obstacles are an enabling mechanism by facilitating the intersection between rebels and migrants. As camping bandits, rebels move between violent extortion and systematic exploitation depending on levels of competition. Finally, I argue that rebels recruit transit migrants using dynamic strategies, including coercive incentives and short-term contracts in which social and ideological requirements are relaxed. Combining quantitative analysis with original interview data, I find significant support for the causal argument and preliminary evidence for my conceptual framework. The findings improve our understanding of rebel organizations and the role of mobile populations in civil conflict.