This article argues that the research on institutionalised inequalities pays too little attention to competing understandings of stratification and the variety of interlinkages between the patterns of stratification and the institutions of international society. Building on the English School and theories of stratification, it develops an analytical framework that conceptualises these ‘stratificatory interlinkages’ as a twofold decision: firstly for a coupling – instead of a decoupling – of institutional characteristics to patterns of stratification and secondly for a specific classification scheme and type of interlinkage. The article draws on empirical examples from the League of Nations and other interwar international institutions to demonstrate that different understandings of stratification and classification schemes were used for different institutional purposes, for example, voting rights and the apportionment of budget expenses. In addition, it proposes four analytical dimensions that allow mapping the variety of classification schemes and types of interlinkages that were chosen for institutionalised inequalities. The dimensions relate to the composition of the reference group, the decision-making about the classification scheme, the institutional purposes, and the institutional form of the interlinkage. The variety of stratificatory interlinkages entails a more variable and diverse relation between stratification and institutions than usually assumed.