The process of European integration and policy?making is sometimes rather puzzling. On the one hand, it is well documented that with respect to the implementation of European legislation member states tend to do less than they are supposed to do. On the other hand, it is striking that with respect to the implementation of the Council Directive 91/440 on the development of the Community's railways many member states went far beyond the minimum required by the European legislation. We argue that these differing evaluations of implementation success can be traced to different implementation approaches, which may be termed the ‘compliance approach' and the ‘support?building approach'. While the first is directed at prescribing domestic reforms from above', the latter aims at triggering European integration within the existing political context at the national level. Here, successful implementation refers to the extent to which European legislation triggers domestic changes by stimulating and strengthening support for European reform ideas at the national level. In this respect, European legislation can influence the domestic arenas in basically three ways: by providing legitimisation for political leadership, concepts for the solution of national problems, and strategic constraints for domestic actors opposing domestic reforms.