The European Union (EU) aims to promote peace. This research investigates the saliency of a European identity for children from majority and minority groups in four conflict-affected societies in Europe (Croatia, Kosovo, Northern Ireland (NI), and Republic of North Macedonia (RNM)). These sites represent a range of relations with the EU (e.g., leaving the EU, an EU member, wanting to join the EU). Participants included 442 children aged 7 to 11 years, evenly split by gender and group status (Croatia n = 90; Kosovo n = 107; NI n = 60; RNM n = 185). After a draw-and-tell task to prime European identity (vs. ingroup or control condition), we measured children's identification with Europe, outgroup attitudes and prosociality. Although the European identity prime was not effective, children's strength of European identity varied by site and group status and related to more positive attitudes and prosociality towards the conflict-rival outgroup. Implications for the future of the European project are discussed.