Amid Brexit, rising populism and conflicts over EU solidarity in the covid-19 crisis, this project studies the dynamic relationship between EU institution building and collective identity. The EU has accrued political authority over nearly half a billion citizens, even in policy areas that are closely linked to national sovereignty. However, political identities are still primarily tied to the member states and many people do not identify as European. The central theories of European integration offer contrasting views on the EU institutions-identity-link – some expect a spillover from institutions to identity, while others expect identity to constrain EU integration, but none can fully explain it.