We propose that the European Union (EU) should be used in citizenship education as a possible vehicle for citizens' influence on issues outside the reach of the nation-state. Citizenship education thus ought to include the EU as an arena for political action and relevant "EU knowledge" ought to be part of the curriculum. Concepts from the German politische Bildung tradition are used to discuss what should be the content of an education aiming at educating young people to (become) democratic citizens and the level of competence required in order to function as a democratic citizen. The "reflecting spectator" is given special attention. Environmental issues are chosen, for three reasons, to show how EU education can be part of citizenship education: the transborder character of environmental problems, the multilevel responsibilities connected to them, and the fact that virtually all European environmental policy is made in, or in close association with, the EU.