While a number of movements seek state secession, the majority never achieves internationally recognized statehood. Paradoxically, some movements that have succeeded have had weaker claims to statehood than many movements that have failed. Regional Politics and State Secession seeks to explain the variation in outcomes for secessionist movements and explores the reasons for why some movements succeed when so many fail. The author proposes a novel theory of secession based on the politics of the region, with the argument that only those secessionist movements that have the support of regional state and institutional actors will succeed in achieving internationally recognized statehood. Through an analysis of six movements across three regions, this book demonstrates why and how regional actors hold the key to understanding when a secessionist movement will find success. This work will appeal to an interdisciplinary academic audience. It lies at the intersection of international relations, international law, and comparative politics. While its core argument is based in international relations, its engagement with legal issues and its in-depth case studies, make it particularly relevant for those interested in international law and comparative politics.