There has been an explosion of interest in recent years in cosmopolitanism, as both political philosophy and object of sociological investigation. In the empirical sociological literature, there is a strong tendency to present Western cosmopolitan thought as purely theoretical in nature, devoid of empirical referents and underpinnings. This article re-narrates the history of cosmopolitan thinking – stretching from ancient Greece and Rome through Kantian philosophy to the time of Durkheim – to demonstrate that this is a caricature, and that there are important empirical and sociological elements in cosmopolitan thought. This fact must be acknowledged in future cosmopolitanism studies, so that political philosophy and sociological analysis are no longer seen to stand in unhelpful opposition to each other, and such that broader, unproductive divisions between the empirical and normative domains are transcended.