This special issue sets out to examine aspects of German politics, philosophy, and society through the multifaceted lens of cosmopolitanism. A complex and contested concept, cosmopolitanism has particularly important implications for the study of contemporary nation-states, as conventional understandings of bounded territory and sovereignty are reassessed in the context of globalization, migration and transnationalism. Accordingly, this introduction aims to outline several key strands of cosmopolitan thought with reference both to contemporary Germany and the wider global conjuncture, in order to provide a conceptual framework for the articles that follow. It begins by briefly placing cosmopolitanism in the context of the evolving concepts of German Heimat (homeland) and nation, because contemporary cosmopolitanism can only be fully understood in relation to nationalism. It then looks at the relevance of methodological, political and ethical cosmopolitanism for the study of nation-states today, before introducing the five articles in the special issue.