The principle of policy coherence has been the object of a contentious debate in the European Union’s external relations, though discussions have been limited mainly to its foreign policy and its ability to speak with one voice in the international arena. Despite being institutionalized in the Treaty of Maastricht, policy coherence for development (PCD), which implies taking into account the needs and interest of developing countries in non‐aid policies, failed to make headway in the EU, remaining the unheeded concern of some NGOs and a small group of member states. A change in direction occurred in the early 2000s when the European Commission, taking advantage of a number of favourable conditions and using an astute strategy, managed to set an ambitious agenda for the EU. This article, nevertheless, shows that promoting PCD risks being a ‘mission impossible’ for whoever attempts it due to the interplay of various issues and interests, the different commitment to international development of the member states, and the EU’s institutional framework.