With the move in EU studies from a focus on European integration to Europeanisation, that is from the process of EU formation to its impact on member states, the number and range of theories and methodologies have proliferated. This article embraces such pluralism. Only by considering a full range of factors policy--problems, legacies, preferences, political and institutional capacity, and discourse--from a variety of perspectives--interest-based rationality, historical path-dependencies, social constructions of action, ideas and discourse--can a complete picture of policy change in Europe emerge. Discourse deserves to be emphasised, however, because it is an often missing, but important, approach to explanation. Discourse, as a set of ideas and a process of policy formulation and communication, helps complete our understanding of policy change when put in relation to other factors and perspectives. Where it helps explain--in which institutional settings and when it helps--by exerting a causal influence--are matters for empirical investigation that are explored in the essays included in this volume., Since the mid-1980s, the European Union, together with its member states, has undergone a major process of transformation. First with the race to the single market by 1992, then with [...]