Is there a trend toward the regionalization of peacekeeping? Does regionalization undermine the United Nations (UN) system of collective security? To answer these questions, we present an innovative dataset of peace operations. Covering the 1947–2016 period, the dataset captures every UN and non-UN peace operation, information on mission type, the existence of target state consent and UN authorization. The unit of analysis is the mission. The first analysis of the dataset yields three findings: (1) There is a significant regionalization of peace operations; (2) regions show distinct intervention patterns; and (3) regionalization does not directly challenge the UN authority.