The United Nations (UN) peacekeeping ‘Capstone doctrine’ is the first attempt by the Department of Peacekeeping Operations/Department of Field Support (DPKO/DFS) to formulate a coherent doctrine for peacekeeping/peacebuilding missions beyond Boutros-Ghali’s An Agenda for Peace and the Brahimi Report, which set out a very general approach as opposed to a doctrinal mandate. In the document, the UN lays down a framework for approaching peace operations, and also defines contemporary UN peacekeeping operations. While this document is designed, by and large, as a guide for UN personnel, it is appropriate to evaluate it to determine whether or not Capstone is consistent with theoretical literature. Furthermore, this article will assess how various components of the doctrine are derived from previous experiences. Lastly, this article will discuss how far the Capstone doctrine is consistent with the major paradigms of international relations theory, and will argue that the doctrine reflects the liberal and constructivist paradigms of international relations theory.