This book unravels the centrality of contestation over international institutions under the shadow of crisis. Breaking with the widely accepted image in the mainstream, US-centric literature of an advance of global governance supported by pillars of institutionalized formality, Andrew Cooper points to the retention of a habitual impulse towards concertation related to informal institutionalism. Rather than endorsing the view that world politics is moving inexorably towards a multilateral, rules-based order, he places the onus on the resilience of a hierarchical self-selected concert model that combines a stigmatized legacy with the ability to reproduce in an array of associational formats. Relying for conceptual guidance on the recovery of a valuable component in the intellectual contribution of Hedley Bull, a compelling case is made that concertation represents a fundamental institution as a peer competitor to multilateralism. In effect, the debate over institutional design is recast away from an emphasis on utilitarian maximization towards a wider set of cardinal - and highly contested - questions: the nature of rules at the global level, the salience of institutional clubs, and the meaning and impact of (in)equality and cooperation/coordination among states across the incumbent West/non-incumbent Global South divide.