How do rebel leaders manage splits in their organizations? The leaders of state governments strategically distribute goods to maintain a stable base of power and prevent widespread defections. Do rebel leaders engage in similar behavior? Existing theories of splintering largely overlook the role of rebel group leaders. This paper challenges this existing work and contributes a new theory of splintering in which rebel leaders play a central role in the splintering process. I argue that rebel leaders can leverage their control over group structures, decision-making, and resources to actively manage internal conflicts and stop subordinates from breaking away. However, periods of leadership transition disrupt these tools and provide new motivation and opportunity for splintering. Consequently, organizational splits are most likely when groups transition between leaders. I assess this theory with original quantitative and qualitative evidence from Myanmar. Drawing on field interviews with rebel leaders, I find that leaders employ several tools to manage splintering pressures during Myanmar's controversial peace process. Using original historical data, I show that groups were more likely to split during years of leader transition. Overall, I find evidence that rebel leaders act strategically to shape splintering in their organizations.