As the most developed political organisation beyond the state, the EU has　been regarded by many political theorists as indicative of a major shift towards post- and supranational forms of global governance, as well as offering a model for how such new political forms might be organised. However, as a growing number of political theorists have engaged more closely with the specifics of European integration and the operations of its institutions, these idealisations have largely fallen away. The process of European integration has been less straightforward and far more contested than has been often assumed, while the peculiar nature of the European political community and the uniquely complex organisation of its institutions have presented intriguing challenges to the core categories with which political theory operates. These concepts, which have been developed over the last centuries with the nation-state in mind as the primary example of modern political organization, cannot be applied wholesale to the EU. Concepts such as legitimacy, sovereignty, democracy, identity, citizenship, constitutionalism, representation, solidarity, etc. must be reassessed if they are to be useful for understanding and normatively scrutinising this political entity. This volume brings together some of the most important scholarly contributions over the last decades that have sought to contribute towards developing a political theory of the EU as an idiosyncratic political organisation. These contributions raise issues not only about the feasibility of attempts to construct political forms beyond the nation state, but also the extent to which they may be desirable. A mixed picture emerges from the state of the art: one that emphasises the existence and importance of continuities with the past in the development of international institutions on the one hand, and conceptual and practical innovations that point towards the need to break with the familiar on the other.