In 2013, the International Law Commission (ILC) embarked on a codification project on identification of customary international law, including the role that international organizations (ios) might play in the formation of customary norms. Parallel discussions in the international law academy surrounding the role of ios reflected similar disciplinary anxieties as older debates on ios and law making. In this piece, I argue that the path to understanding ios' governance passes neither doctrines of ios' powers nor restrictive categories such as law making. A shift to 'worldmaking practices' and alternative approaches can help us diversify our subjects of enquiry and the ways in which we understand the 'institutional' dimension of international law. Here, I specifically focus on International Relations constructivism, Foucauldian 'governmentality', and critical political economy approaches. I then conclude with a discussion of international institutional law, interdisciplinarity and critique.