Leadership is widely regarded as a critical factor for the European Union’s ability to act cohesively and effectively as global actor. The siren call for leadership is most often heard when Europe is facing one of its perennial crises, but which actor has the ability to shoulder this responsibility and how? Half a century after Henry Kissinger quipped, ‘who do I call, when I want to call Europe?’, there still seems to be no authoritative person or institution who can speak on behalf of Europe. In this talk, I discuss why European leadership is contested in EU foreign policy. Based on results from a large interview survey with national and European diplomats, I identify a central paradox at the heart of EU foreign policy. While formal European leadership functions and institutions were significantly strengthened with the Lisbon Treaty, the EU has become increasingly rudderless and characterized by informal leadership practices emerging in groups of like-minded EU member states. These new types of informal leadership practices will have significant repercussions on future European-British cooperation in a post-Brexit world.