Abstract Two models of regulatory competition are contrasted, one based on a US pattern of competitive federalism, the other a European conception of reflexive harmonisation. In the European context, harmonisation of corporate and labour law, contrary to its critics, has been a force for the preservation of diversity, and of an approach to regulatory interaction based on mutual learning between nation states. It is thus paradoxical, and arguably antithetical to the goal of European integration, that this approach is in danger of being undermined by attempts, following the Centros case, to introduce a Delaware-type form of inter-jurisdictional competition into European company law.