The paper reviews some social scientific theories which could contribute to the development of a concept of European governance beyond traditional notions of federal state or international organisation. The theoretical argument is based on the culturalist version of neo-institutionalism which stresses the role of ideas in the functioning and transformation of a political order. It is claimed that both globalisation and functional differentiation tranform existing nation-states and shape the emerging European polity. European governance is characterised as poly-centric and non-hierarchical. Finally, different approaches to the legitimation of such a polity are discussed. The paper comes to the result that the emergence of a European political order is part of a process which could necessitate a rethinking of basic social scientific concepts.