The United Nations (UN) has developed a complex and interconnected system of committees, representatives, and missions in support of its peace and security mandate. This article introduces the United Nations Peace Initiatives (UNPI) data set, which provides information on 469 UN initiatives aimed at conflict prevention and crisis management, mediation, peacekeeping, and peacebuilding. The data encompass all initiatives mandated by the UN Security Council, the General Assembly, as well as Secretary General between 1946 and 2015. This includes diplomatic, technocratic, political-development, and peacekeeping missions. UNPI data provide an empirical basis to assess the relative contributions of various UN subsidiary bodies to prevent, manage, and suppress the outbreak and recurrence of conflict. This article discusses the underlying rationale of the data collection, the coding rules, and procedures, and shows how UNPI can be combined with conflict data. Initial analyses show the increased use of different types of UN peace initiatives over time. The UN regularly deploys multiple peace initiatives to a dispute, often with significant periods of overlap. Ongoing hostilities and economic development are found to be key determinants of mission choice. In line with the theme of the Special Issue, the UNPI data set underscores the importance of, and provides a tool through which to examine the, interdependencies between various conflict management efforts.