The European Union (EU) increasingly faces external pressures, ranging from Russia's war of aggression against Ukraine to an economically and politically assertive China to deep changes in the transatlantic relationship with the United States. Whilst external actors and influences always mattered for European integration and EU studies, this article holds that they are more consequential today than in the past. This is because the EU has turned into an institutionally consolidated but, at the same time, internally contested polity. The article provides a conceptual and analytical framework for the study of ‘externalism’. Empirically, it documents differences of externally driven European integration over time and between externally and internally driven integration. Opening avenues for future research, the article suggests a more explicit and systematic study of external factors for the EU's institutional and policy trajectory.