This book presents an overview of inter-municipal cooperation in eight European countries. Each country study sketches its attendant forms, their institutional design, the tasks and competencies attributed to joint authorities of municipalities and the way inter-municipal cooperation operates in practice. Both performance and democratic aspects of cooperation are recurring topics. The last chapter of the book presents a comparative analysis and reflects on the future of inter-municipal cooperation. Inter-municipal cooperation is a phenomenon that, despite its ubiquity, has not been subject to systematic comparative research.