Public opinion research has increased our understanding of the variables affecting endorsement of EU integration. What is less well understood is how comparative identity processes shape EU identification. Drawing on social identity principles, we argue that EU identification is in part affected by tensions between relevant subgroup identities. To illustrate this point, two studies were conducted in UK regions (Wales and Cornwall). Findings confirm our prediction that a comparative context affects EU identity and indicate (a) that levels of EU identity were higher in contexts where regional identity was salient, and (b) that regional identity affected the bases and meaning of EU identification and EU endorsement. Discussion highlights the importance of taking context and intergroup relations into account when examining EU attitudes. Copyright (c) 2009 The Author(s). Journal compilation (c) 2009 Blackwell Publishing Ltd.