The aftermath of the First World War saw manifold efforts to (re-)construct an international community. One striking development of this development was the foundation of various international student organisations. This article analyses the largest of these bodies – namely the International Confederation of Students (Confédération internationale des Étudiants, CIE). The CIE forms the prism through which the article investigates four major aspects of interwar internationalism: nationalism, intellectual cooperation, mobility and radicalism. The CIE brought together the representatives of different national unions of students and thus involved activists that could cast themselves as future leaders. It portrayed its activities as 'apolitical', embracing an internationalism that sought to consolidate, rather than overthrow, the international order. To this end, the organisation cooperated with the League of Nations, particularly in the realm of student travel. Yet, despite its discourse of peace and non-partisanship, the CIE suffered from manifold national divisions and maintained an uneasy relationship with the political developments of the period. In this context, the article shows how, rather than being the domain of impractical idealists, internationalism provided an arena for the pursuit of competing national and political agendas.