This book studies recent attempts to restructure maritime security sectors through capacity building. It innovates both theoretically and empirically. It proposes a new framework for understanding maritime capacity building, drawing on work in peacebuilding and security sector reform. The framework is then applied across empirical case studies from the Western Indian Ocean (WIO) region written by scholars from the Global South. The WIO region is a paradigmatic case to study maritime security and capacity building in action. Countries in the region face the full gamut of maritime security challenges, while their indigenous capacities to deal with these are often weak. In consequence, the region functions as an engine of innovation for maritime capacity building more widely. The lessons and best practices from the region have importance consequences for addressing maritime security across the globe.