When do UN peacekeeping operations implement their mandates?

Under what conditions do UN peacekeeping operations (PKOs) implement the tasks in their mandates? Contemporary PKOs are expected to fulfill increasingly fragmented mandates in active conflict zones. Drawing on principal-agent and constructivist accounts of the performance of international organizations, we argue that these two trends --increasingly fragmented mandates, increasingly implemented amidst violence-- hinder PKOs from pursuing mandated tasks, undermining their legitimacy in the eyes of the Security Council, troop-contributing countries, and host-governments. Combining new datasets on PKOs activities and mandates in Africa (1998-2016) and using instrumental variables and two-way fixed effects models, we find that that mandate fragmentation is negatively correlated with mandate implementation, especially for peacebuilding tasks. Ongoing violence is also negatively correlated with the implementation of peacebuilding, but not with security-related tasks. We show that this is likely due to the offsetting effects of violence perpetrated by governments and rebels, as PKOs are better equipped to respond to the latter