This article addresses the character and potential of the radical cosmopolitanism that is currently flourishing within the social sciences. I explore how cosmopolitanism is articulated in a number of disciplines–including international law, international relations, sociology and political philosophy–and how it conceives of its own age. I focus first of all on the timeconsciousness that informs the cosmopolitan representation of modernity, in particular its projection of a rupturebetween the old ‘Westphalian’ order of nation states and the advancing cosmopolitan order of the present, and, second, on the nature of cosmopolitan critiques of nationalism, socialism and ‘modernist’ social and political thought in general. Behind this focus lie a question over the extent to which cosmopolitanism replicates in its own normative proposals the defects of that which it criticizes, and another question over the means by which the critical kernel of contemporary cosmopolitanism can be separated from its doctrinal shell.