This study explores the issues underlying current and longstanding concerns over the "creeping competences" of the European Union. A fundamental question since the early origins of the European Union in the functionally limited economic, coal and steel and atomic energies communities of the 1950s has been the legitimate scope and limits of its powers of action, and the relationship between these powers and those of its component Member States. This issue, which centres on the legitimacy of different levels and fora of government within a complex and growing economic and political entity, has been brought to prominence again by the constitutional agenda set by the European Council at Nice. Specifically, it has been highlighted by the call for a more precise delimitation of competences between the EU and the Member States. This book seeks to identify some of the issues of democracy and legitimacy which underlie the anxiety of state and sub-state entities over the "creeping competences" of the EU on the one hand, and the questions of capacity and interdependence which pull in the direction of supranational and transnational action and governance on the other.