Abstract: In war-torn countries, elections are held to support peacebuilding, but they sometimes trigger new violence. While PKOs regularly accompany electoral periods, we lack systematic knowledge on how they influence election-related violence. I argue that variation in peacekeepers’ activities is fundamentally important: Only if PKOs assist with securing and organizing elections, can they reduce election-related violence. Using novel data on PKOs’ election-related activities and accounting for endogeneity in both peacekeeping deployment and activities, the analyses of all 630 elections in conflict-affected countries support this expectation. The result implies that the design of PKOs is crucial for effectively managing post-war political transitions.