This book questions the idea that mobility of people should be controlled, either at the international border or based on the national citizenship with which a person was born.The book describes the magnitude of the deadly results of contemporary borders worldwide, problematizes the concept of the border and then develops arguments for a world without borders. It uses a dialectical approach to contemplate alternative possibilities, ranging from practical and feasible to the utopian distant future, drawing on the theoretical work of thinkers such as Ernst Bloch, David Harvey, and Henry Lefebvre, with international empirical examples of policy practices on migration and claims of belonging.