What is citizenship? This question goes back to the political philosophy of Aristotle, and how one answers it will be decisive in determining one's vision of political life. In the last ten to fifteen years, the question of citizenship has aroused a renewed set of extremely lively debates within political philosophy, and Iris Marion Young has certainly occupied an important place within these theoretical debates. In particular, Young--especially in her seminal article, "Polity and Group Difference: A critique of the ideal of universal citizenship"--has presented a sharp challenge to all political theorists who are in some broad sense intellectually nourished by the tradition of civic republicanism and who think about the theme of citizenship under the influence of civic-republican conceptions. In essence, Young's argument is that the practices of contemporary liberal society show that the implicit normative promise contained in the idea of a universal citizen identity has not been fulfilled, and therefore we must rethink this notion from the ground up. The purpose of my essay is to review the arguments that constitute Young's challenge to the civic-republican tradition, with a view to clarifying the following questions: Is Young's political theory aimed at a reconstruction of the idea of citizenship on a normatively more sound basis? Or does her project imply a rejection of the idea of citizenship, and its displacement by an alternative understanding of political membership?