Europeanization can be conceived of as a two-fold process. It involves the evolution at the European level of a distinct governance system, a new set of political structures and processes, which interact with the established ones of the member states. Hence, Europeanization entails a “bottom-up” and a “top-down” dimension. The former emphasizes the emergence of European institutions as a set of new practices and rules, structures of meaning, and resources, while the latter refers to the effect of these new institutions on the institutions of the member states. The causal processes of Europeanization entail both dimensions. However, most studies distinguish between them analytically, focusing on either of the two dimensions.

For a long time, research on Europeanization focused on the “bottom-up” dimension, which has also been referred to as “Europeification” (Andersen and Eliassen 1993) or “Vergemeinschaftung” (communitarization). Europeanization is analyzed as a process of institution-building at the European level driven by the progressive transfer of competencies from the member states to the European Union (formerly European Community). Theoretical and empirical studies focus on the role and interaction of different actors, both European (European Commission, European Parliament, European Court of Justice, Committee of the Regions, EU interest groups) and national (member state governments, interest groups, regions) in European policy-making. The underlying dynamics, the nature, and the final outcome of the emerging European system of governance have been the main dependent variable.