updated and revised version of a 2009 book chapter in Dehousse. R. (2009), European Policies, Paris, Presses de Sciences Po. This notice raises two questions: is it possible to identify, at European level, common forms of expressing concerns about environmental issues, formulating public problems and choosing appropriate solutions for dealing with them? Or is the historical legacy of national public policy systems the best way of analysing the development of European environment policy? The idea here is that the relationship established, from the outset of this policy, between environmental protection and the completion of the single market explains the political, institutional and cognitive deadlock in European environmental policy, which remains unhomogeneous, highly interconnected with other levels and policy areas and unevenly developed.