For the last three decades, the prospect of ‘water war’ between riparian countries has been the subject of intense academic and popular interest. However, while international water wars are very uncommon, subnational water conflicts – disputes over water that occur between groups or provinces within countries as opposed to between countries – occur regularly. Moreover, increasing water scarcity and climate-related challenges raise the possibility of making the sub-national politics of shared water resources more challenging in future. In this book, Moore has not focused on water conflicts at the international level but has examined subnational water conflicts, a subject that has not previously received sufficient attention as it demands. In a federal system, the role of subnational actors in water politics has increased worldwide as a result of increasing emphasis on decentralization. The disputes between subnational water users in shared river basins often persist in spite of attempts by central governments to resolve them with the help incentives and/or threats. The book carefully analyzes the interaction of subnational actors to explain these dynamics of conflict and cooperation in shared river basins. With the help of in-depth case studies of subnational water sharing in the United States, India, China, and France, it finds that while political decentralization provides the grounds for the dispute, identity politics motivates the politicians to create a competing discourse over the shared water. However, the active and regular participation of these competing subnational actors in managing the shared water can help to build cooperation. The book also includes case study-specific as well as general policy recommendations.