This book seeks to answer the question "Which institutional architecture for which kind of democracy for the EU?" by bringing two important recent debates together - the institutional analysis of the Union and its democratic assessment. The book examines a series of institutional architecturesin light of the democratic quality of the processes and decisions generated by them. The discussion of these various institutional architectures is preceded by an analysis of the democratic values and principles according to which institutional architectures and governance structures should be assessed. The first part of the volume starts from key democratic principles and indicateswhich institutional architectures are most likely to embody them. The second part is dedicated to those institutional architectures that best describe the current state of the European Union and its likely future development, particularly given the impact of the current economic crisis. Thefundamental belief that animates this volume is that it is only by paying attention to the democratic legitimacy of the Union that the process of European integration may hope to be sustainable, particularly in the face of the difficult economic crisis that the members of the Euro-area and the Unionin general are experiencing.