ABSTRACT In civil conflicts, the relations of rebel groups with civilians are largely influenced by the rebels’ capabilities. Seeking external resources to enhance their military efforts and resilience, rebel groups’ access to those resources shapes their war strategies, including violence against civilians. Unlike the extant research drawing on highly aggregated designs, we argue that not every form of support affects rebels’ violent behaviour in the same direction. In this study, we test whether different forms of external support are associated with the level of rebel violence against civilians by using comprehensive data on foreign support to rebel groups in intrastate conflicts between 1989 and 2017. The findings support the need for disaggregation of foreign support to understand better the dynamics in this relationship. The results show that external support in the forms of access to infrastructure, from both state and non-state actors, and troops from non-state actors are associated with a decrease in civilian victimisation.