Varieties of informal intergovernmental organisations: how differences in design matter for informal governance

Abstract Informal intergovernmental organisations (IIGOs) like the G20 and the BRICS are omnipresent in current international affairs and frequently portrayed as global crisis managers or steering committees. While such metaphors help in understanding their role in global governance, they tend to overlook their varying institutional features and potential for informal governance. Not every IIGO acts globally, addresses multiple issues or steers through orchestration. Hence, this paper asks how variations in IIGOs’ institutional design shape their capacity for informal governance. Building on a discussion of their agency and institutional variety, it develops a typology that distinguishes and illustrates key IIGO types according to their issue scope and members’ collective capabilities. It argues that both features shape IIGO’s capacity for informal governance and holds that especially general-purpose IIGOs with comprehensive collective capabilities are likely to draw on the full spectrum of informal governance mechanisms—including self-binding commitments, outreach, and orchestration. Other IIGO types are either restricted in the scope of issues they address or in their collective capabilities, and thus in their overall governance capacity. With that, it raises questions about existing debates on the creation of IIGOs and their contribution to global governance, and indicates directions for future research on their effectiveness, legitimacy, and change.