Rainer Bauböck is the world’s leading theorist of transnational citizenship. He opens this volume with a question that is crucial to our thinking on citizenship in the twenty-first century: who has a claim to be included in a democratic political community? Bauböck’s answer addresses the major theoretical and practical issues of the forms of citizenship and access to citizenship in different types of polity, the specification and justification of rights of non-citizen immigrants as well as non-resident citizens, and the conditions under which norms governing citizenship can legitimately vary. This argument is challenged and developed in responses by Joseph Carens, David Miller, Iseult Honohan, Will Kymlicka and Sue Donaldson, David Owen and Peter J. Spiro. In the concluding chapter, Bauböck replies to his critics.