As European integration has become politicised over the last several decades, scholars have paid keen attention to the role of identity in shaping political conflicts and contestation in Europe. This article investigates the microfoundation of the political divide over European integration by building on and extending theories of social identity and recent studies on affective polarisation. Large-scale survey experiment data from 25 European Union member states are analysed to explore the extent of divides over European integration. This analysis shows a statistically significant and substantively large magnitude of the divide based on European identity. Moreover, results show that this divide over European integration deserves particular attention as it is largely driven by out-group animosity, rather than in-group favouritism. Lastly, results show that electoral context, such as electoral salience, involvement in elections, elite polarisation, and the strength of Eurosceptic parties, influences the intensity of the European divide.
