This book addresses one of the most relevant challenges to the sustainability of the European Union (EU) as a political project: the deficit of citizens' support. It identifies missing elements of popular legitimacy and makes proposals for their formal inclusion in a future Treaty reform, while assessing the contribution that the EU may make to global governance by expanding a credible democratic model to other international actors. The contributors offer perspectives from law, political science, and sociology, and the 15 case studies of different aspects of the incipient European demos provide the reader with a comprehensive overview of these pertinent questions. The edited volume provides a truly interdisciplinary study of the citizens' role in the European political landscape that can serve as a basis for further analyses of the EU's democratic legitimacy. It will be of use to legal scholars and political scientists interested in the EU's democratic system, institutional setup and external relations.