Although some rebel groups work hard to foster collaborative ties with civilians, others engage in egregious abuses and war crimes. We argue that foreign state funding for rebel organizations greatly reduces incentives to “win the hearts and minds” of civilians because it diminishes the need to collect resources from the population. However, unlike other lucrative resources, foreign funding of rebel groups must be understood in principal-agent terms. Some external principals—namely, democracies and states with strong human rights lobbies—are more concerned with atrocities in the conflict zone than others. Multiple state principals also lead to abuse because no single state can effectively restrain the organization. We test these conjectures with new data on foreign support for rebel groups and data on one-sided violence against civilians. Most notably, we find strong evidence that principal characteristics help influence agent actions.