Europe’s woes mark a new chapter in the longstanding theory/history nexus in European studies. The euro crisis has brought integration theory back onto the scholarly agenda and highlighted the value of neo-functionalism – and more precisely its key ‘spillover’ mechanism – as a framework for interpreting current politico-institutional dynamics in the European Union. We are, however, at a particular point of the neo-functionalist narration, in which the transition from low to high political integration has opened a phase of political fluidity that makes ideas and political leadership crucial in determining the future course of integration. In this phase, the positive scheme of neo-functionalism and the normative one of federalism come together, bringing the intellectual trajectory begun after WWII to full circle. Whether this new encounter will result in further integration depends primarily on the content of new federalist ideas, the emergence of an effective European leadership, and the presence of a favourable international environment. For all three factors, the record so far has been mixed at best.