Abstract: UN peacekeeping operations (PKOs) promote elections to support transitions from war to institutional politics. Yet, elections renew competition and sometimes reignite violence. Can PKOs mitigate election violence? Beyond the present research focus on PKO personnel numbers, this study argues that we need to consider peacekeepers’ activities on the ground to answer this question. Increasing troop numbers alone may not function as an effective means to reduce election violence. More PKO troops result in higher costs and, consequently, greater international pressure for PKO withdrawal. Therefore, PKOs may advocate earlier elections to hand-over responsibilities to an elected government. Yet, early elections are also associated with a higher risk of election violence. In addition, larger PKOs are more effective in preventing battlefield victory. By consequence, spoiler may target “unprotected” elections to undermine a peace deal. However, if PKOs are designed to secure and assist the organization of elections, more personnel may be associated with fewer events of election violence. Increasing personnel can strengthen PKOs’ activities to protect voters, candidates and election workers, optimise their material and logistical election support and signal greater international engagement for peaceful elections. Employing a novel dataset on PKOs’ activities during electoral periods and accounting for endogeneity in both deployment and policy choice, the statistical analysis of 445 elections in war-torn countries provides robust evidence that the impact of PKO personnel on electoral peace is conditional on PKO election-related activities.