Derived from the ancient Greek for ‘world citizenship’, cosmopolitanism offers a radical alternative to identities and cultural practices built on the idea of the nation: cosmopolitans imagine themselves instead as part of a global community that cuts across national and linguistic boundaries. This book argues that fin-de-siècle writing in English witnessed an extensive and heated debate about cosmopolitanism, which transformed readers’ attitudes towards national identity, foreign literatures, translation, and the idea of world literature. It offers a critical examination of cosmopolitanism as a field of controversy. While some writers and readers embraced the creative, imaginative, emotional, and political potentials of world citizenship, hostile critics denounced it as a politically and morally suspect ideal, and stressed instead the responsibilities of literature towards the nation. In this age of empire and rising nationalism, world citizenship came to enshrine a paradox: it simultaneously connoted positions of privilege and marginality, connectivity and non-belonging. Chapters on Oscar Wilde, Lafcadio Hearn, George Egerton, the periodical press, and artificial languages bring to light a variety of literary responses. The book interrogates cosmopolitanism as a liberal ideology that celebrates human diversity and as a social identity linked to worldliness. It investigates its effect on gender, ethics, and the emotions. It presents English-language literature of the fin de siècle as a dynamic space of exchange and mediation, and argues that our own approach to literary studies should become less national in focus.