This book suggests that more can be said about cosmopolitanism than either the bold endorsement of a world state or the humble recognition of the equal moral worth of individuals, which makes everybody cosmopolitan. Identifying problems with the traditional concept and disentangling a variety of positions within the cosmopolitan paradigm, it introduces the more refined concept of cosmopolitanism as nonrelationism, which denies underived special duties among fellow citizens or other related individuals, such as family members or friends. Cosmopolitanism as nonrelationism promises to overcome an entrenched debate wherein everybody is a cosmopolitan, and brings back the radical character traditionally associated with the term. It portrays cosmopolitanism as a distinct and thorough position challenging classic proponents such as Barry, Caney, Nussbaum, and Pogge, and questioning their theories’ cosmopolitan character. Cosmopolitanism as nonrelationism has consequences for world politics without prescribing any unfeasible global order: It establishes normative criteria for evaluating institutions and provides guidance for the development of new ones.