This article interrogates the questions evoked by the curious case of ‘schools’ of thought in International Relations (IR) through the twin perspectives of the sociology of knowledge and geopolitics of knowledge. Drawing inspirations from the tradition of the sociology of IR pioneered by E. H. Carr, the paper first explores how geo-epistemic diversity can help understand the sociologically problematic nature of IR knowledge production in the existing discipline. Taking cues from Randall Collins’s sociology of philosophies, the article moves to identify four clusters of sociological conditions and dynamics that, we argue, facilitate the formation and sustain the operation of schools of thought in IR. Taking seriously the recent insight from geopolitics of knowledge, the article then looks at why and how school labelling constitutes a battleground for contestation and legitimation of knowledge. While the ‘core’ uses the school label to create a parallel, and explicitly inferior, universe of knowledge production to localize theoretical noises from the peripheries, the school label, we argue, has been proactively appropriated by those at peripheries and semi-peripheries for three strategic purposes: to engage in a purposely contentious politics, to question the claim of the American ‘core’ as the creator, depositor, and distributor of universal knowledge, and to unveil the geo-historical linkage between the political and the epistemic. School labelling matters, we further argue, because it has become a site of contestation of geopolitics of knowledge and reflects the perils and promises in our collective pursuit of constructing a truly global IR.