We propose that collective support for European integration is mani‐fested in 2 distinct forms: first, as engagement in socio‐political action by citizens who seek to change their nation and its status in Europe. Second, it is manifested as a transnational acculturation process that impacts on both nations and their citizens. These processes potentially engage social identities at 3 levels: national, European and as supporters of the European integration. Here, we examine these different levels of identification as part of a model predicting collective support for the European integration. To capture the dimension of transnationality, we collected data from 2 Romanian samples, 1 of participants living in their country of origin (N = 203), and 1 of participants living as migrants outside Romania (N = 196). We found that identification as a pro‐integration supporter flows from European and Romanian national identifications and is an excellent predictor of collective support for European integration in both its forms. We conclude by discussing how our findings can be applied to the design of intervention strategies and policies to promote support for the European Union and the integration process in the current socio‐political climate (where the unity and the very existence of European Union are under threat).