This chapter examines the relationship between social democracy and integration in Europe, arguing that Euroscepticism has been an ever-present aspect of social democracy. The chapter places this relationship in the context of the broader political economy of Europe. It argues that social democratic parties were initially slightly wary of integration, for both ideological and national reasons. But as social democratic parties became regular participants in government, they became less radical and began to accept the European Community. This positive engagement changed when Europe shifted from a broadly social model to a more neoliberal one. The European Union imposed greater constraints on social democracy, but by this stage the parties were too deeply embedded in the EU—they had succumbed to an integration ‘trap’. The chapter concludes that in the wake of the financial crisis, demands for a turn away from neoliberal market solutions have gained greater traction, but the integration ‘trap’ means that social democratic parties have struggled to find a convincing ‘alter-European’ message to match the mood.