This article examines how ideas about what is to be governed, how and bywhom, are made sense of in European Union governance. It interrogates the complex relationships of knowledge generation, knowledge circulation, expertise and policy-making in two contrasting policy areas. In social policy, the emergence and later privileging of a discourse of the ‘social investment state’ are traced through the ‘linked ecologies’ (Abbott, 2005) of formal ‘European’ social science research, academic politicians and the Open Methods of Co-ordination. In security research policy, mētis ,or practical knowledge (Scott, 1998), has enabled major European corporations to assert a privileged discursive and political position in the ‘linked ecologies’ of formal scientific research, product development and EU policymaking. These two cases demonstrate the partial integration of elite discourses with scientific rationalities into EU governance. In each case, the generation of knowledge and expertise is articulated in governance practices in ways that generate politically specific and limited – but not the same – versions of ‘the’ EU to be governed.