According to Jürgen Habermas's notion of pouvoir constituant mixte, the EU needs to derive its democratic legitimacy from a dual subject, consisting of the community of European citizens on the one hand and the communities of state citizens on the other. In this introduction, I outline some of the basic ideas behind the pouvoir constituant mixte, situate the category within wider debates about democracy in the EU and the future of European integration, and provide a brief summary of the symposium contributions.