The UN Security Council has mandated and overseen a wide range of mission transitions, typically as peace operations are gradually drawn down and closed. Nonetheless, the Security Council appears to confront many recurring challenges in mandating transitions, often repeating approaches that worked poorly in the past. With several large peace operations undergoing or likely to start transitions in the coming period, along with a range of special political missions that may face transitions, there is an urgent need to understand better (1) how Security Council language and approaches to mission transitions has evolved over time, (2) what dynamics influence transitions mandates in the Council, and (3) how to improve Council practice on mandating transitions. The following project has been designed to address these questions, and to offer Security Council members in particular, but also UN Secretariat staff, and mission leadership, a set of policy-level recommendations for developing and advocating more effective, sustainable transitions processes going forward. As a result of this project, UN transitions will be planned and managed in a proactive, integrated and forward-looking manner, resulting in the UN being better positioned to provide efficient and effective support to host countries as they progress towards peace and sustainable development.