States covet leadership and staff positions in international organizations. The posts of civilian leaders and force commanders of United Nations (UN) peacekeeping operations are attractive to member states. In selecting peacekeeping leaders, the UN Secretariat balances three considerations: satisfying powerful member states by appointing their nationals; recognizing member states' contribution to the work of the organization; and ensuring that leaders have the necessary skill set. We investigate appointments of more than 200 civilian and military leaders in 24 UN missions, 1990-2017. We find that contributing troops to a specific mission increases the chances of securing a peacekeeping leadership position. Geographic proximity between the leaders' country and the conflict country is also a favorable factor whose importance has increased over time. Civilian leaders of UN peacekeeping operations tend to hail from institutionally powerful countries, while military commanders come from major, long-standing troop contributing countries. Despite some role that skills play in the appointment process, the UN's dependence on troop contributors, together with its reliance on institutionally powerful states, can be a source of dysfunction if it prevents the organization from selecting effective peacekeeping leaders. This dynamic affects other international organizations that have significant power disparities among members or rely on voluntary contributions.