Under what conditions do sponsors directly intervene in the target state’s civil conflicts? While previous research on state sponsorship for the rebels tends to focus on how ties between the two can influence their interactions, this article argues that the sponsor is more willing to provide combat support when the target state is under the rule of a personalist regime. Due to a lack of internal constraints, personalist leaders are more likely to pursue aggressive foreign policies. The high degree of policy flexibility also makes personalist regimes unreliable partners for negotiation. To avoid future instability, rival states are more likely to use civil conflicts as opportunities to weaken the personalist regime. Military ineffectiveness under personalist regimes also lowers the cost of combat support and potentially allows sponsors to reap more material benefits from the civil conflict. Utilizing comprehensive data on personalism and rebel sponsorship, I find support for this argument.