Organised population transfers, expulsions, and exchanges have been a surprisingly common feature of international politics, but little is known about the diplomacy that has accompanied such processes. This project will develop the first comprehensive dataset of incidents of state-organised forced migration, from 1900-present, and their relationship to bilateral and multilateral diplomacy. The project asks three questions: 1) What diplomatic interests, tools and processes have shaped instances of state-organised forced migration? 2) What have been the diplomatic causes and effects of state-organised forced migration, and 3) How do these relate to other international political arenas? This interdisciplinary project fills an important gap in our understanding of migration and foreign policy, including its evolution over time and its regional and geographic variation. The resulting dataset, case studies and mixed method analyses will be an important resource to policymakers and scholars of migration, international relations, diplomatic history, international law and forced migration studies.