In an era defined by shifting distributions of power, states are not only pushing for change in formal international organizations, they are increasingly using informal intergovernmental organizations (IIGOs) to mediate change. Why and how do states use IIGOs – institutions without a treaty or secretariat – to manage global power shifts? IIGOs are useful for states on both sides of the power shift. Established powers use IIGOs for system management through ‘collaboration’ and strengthening the ‘hegemonic consensus’ to preserve their institutional privileges while adapting to changing power realities. Rising powers use IIGOs to redistribute through ‘power bargaining’ and ‘rhetorical coercion’ to strengthen their institutional roles without overly disrupting the current order. Established and rising powers also work together to use IIGOs for integrative strategies including ‘cooptation’ and ‘principled persuasion’, creating a mutually beneficial solution that accommodates both increased demands but also mounting responsibilities. IIGOs help states manage power transitions by providing flexible institutional arrangements that facilitate bargaining without freezing outcomes in permanent institutions while the power distribution evolves. We provide case vignettes of the G7 (system management) in the early phase of a power shift, BRICS (redistributive strategies) in the middle phase, and the G20 (integrative strategies) in the later phase.
- Policy makers should use informal intergovernmental organizations (IIGOs) to mediate power shifts because their flexibility and informality provide a forum for gradual adaptation before long run solutions are known.
- Legacy powers seeking to maintain status quo institutional arrangements should use IIGOs to build a consensus and collaborate with like‐minded partners.
- Rising powers seeking to strengthen their institutional positions without overly disrupting prevailing cooperative arrangements should use IIGOs to facilitate bargaining and rhetorical tactics.
- Legacy and rising powers should work together through integrative IIGOs using mutual cooptation and persuasion to respond to a shifting distribution of power.
- IIGOs offer many benefits to states – including flexibility, transition management, and the protection of sovereignty – but they lack legitimating factors such as transparency and accountability.