This book examines and investigates the legitimacy of the European Union by acknowledging the importance of variation across actors, institutions, audiences, and context. Case studies reveal how different actors have contributed to the politics of (re)legitimating the European Union in response to multiple recent problems in European integration. The case studies look specifically at stakeholder interests, social groups, officials, judges, the media and other actors external to the Union. With this, the book develops a better understanding of how the politics of legitimating the Union are actor-dependent, context-dependent and problem-dependent. This book will be of key interest to scholars and students of European integration, as well as those interested in legitimacy and democracy beyond the state from a point of view of political science, political sociology and the social sciences more broadly.