The chapter develops an argument in favour of an interpretation of the European Union (EU) as a compound union. To do that, it will confront the main interpretations of the Union that have accompanied its development, that is the economic community’s view and the two rival political interpretations of the EU as an intergovernmental or supranational organization. The euro crisis has highlighted the difficulty, if not impossibility, of keeping those different visions of the EU within the same project. The euro crisis has brought to the surface the existence of more than one Union, none of them able to give a coherent perspective of development to the EU. From this analysis, the chapter elaborates a proposal for setting up a compound union, based on the euro area member states and structured around an original model of separation of powers.