Although Aristotle's quotation was written more than 2,350 years ago, it raises questions about citizenship that are still relevant today. Indeed, over the course of the last two millennia (and especially the past 50 years), scholars have focused much more on the state than on citizenship. Even leaving aside modern-day oligarchies, and just focusing on liberal democracies, Aristotle's questions appear timely within the recent context of globalization, large-scale migration, and the decline of many elements of nation-state sovereignty. Given the extent of variation within contemporary democracies, one could perhaps simply rephrase the last clause in the above quotation as follows: “the person who is a citizen in one democracy is often not a citizen in another.” But to what extent, and for what reasons, is this the case? And what are the implications for immigrant integration, national identity, and democratic politics in the modern era?