Dual/multiple citizenship has become a widespread phenomenon in many parts of the world. This acceptance or tolerance of overlapping memberships in political communities represents an important element in the ongoing readjustment of the relationship between citizens and political communities in democratic systems. This article has two goals and parts. First, it evaluates dual citizenship from the perspective of five normative theories of democracy. Liberal and republican as well as multicultural and deliberative understandings of democracy deliver a broad spectrum of arguments in favour of dual citizenship. Only communitarians fear that dual citizenship endangers national democracies. Nevertheless, empirical evidence and national policies largely contradict these fears. The second part of the article reverses the perspective and shows that most theories of democracy do not only legitimate and facilitate the acceptance of dual citizenship - the phenomenon of multiple citizenships induces innovation in democratic theory in turn. A second look at the relationship between dual citizenship and theories of democracy reveals that dual citizenship stimulates refinements, expansions and reconceptualisations of these theories for a transnationalising world.
