Recent literature has linked this politicization to the growing authority of the international level but also points to significant variation of politicization across time and international organizations. Thus, our contribution provides a more refined view on the nexus of international authority and politicization. Distinguishing several policy functions of international organizations, we discuss which institutional design features raise or suppress the probability that international decisions are politicized beyond the set of directly participating executive actors. Along features such as the discretion of international bodies in agenda setting, the inclusiveness of the various decision-making stages, and the stringency of enforcement rules we offer a classification of international organisation from which testable hypotheses on the nexus of international authority and its politicization can be derived.