UN peace missions are constantly evolving. Yet, we lack a detailed understanding of the shifting types and objectives of peace missions beyond broad categorizations that distinguish for instance between observer, traditional, multidimensional, and peace enforcement missions. To address this gap, we present the UN Peace Mission Mandates (UNPMM) dataset. With global coverage, 30 years of data between 1991 and 2020, a broad scope that includes peacekeeping and political missions, and information on 41 mandate tasks, the UNPMM represents one of the most detailed and up-to-date datasets on UN peace mission mandates. We use it to highlight how mission types, objectives, and specific tasks have changed since the end of the Cold War, and to analyze what factors influence the kind of missions the UN is willing to authorize. The descriptive statistics and empirical analysis reaffirm the need for a greater disaggregation of data on UN peace missions and their mandates.