This paper explores some of the major changes in the practices of international organizations that have occurred in the decades since The Doctrine of the Legal Equality of States was published. First, much international law-making in contemporary international organizations consists of regulation and administration whose creation, content and application differs significantly from that of traditional forms of international legislation associated with international organizations. Second, in a highly fragmented international legal order, twenty-first century international organizations increasingly interact with each other in a wide variety of law-making and operational capacities. Given these changing roles and activities, it is no longer sufficient to view international organizations primarily as fora through which other actors – typically states – pursue their interests. Rather, twenty-first century international organizations often pursue their own goals and agendas as autonomous actors in international affairs. These developments have rendered traditional debates over sovereign equality within international organizations substantially less salient than they were when Legal Equality was written. In the future, the cutting-edge doctrinal and jurisprudential issues raised by twenty-first century international organizations largely will arise out of interactions among international organizations. As a result, legal scholars should shift their attention from inter-state interactions and processes within any particular IO to interactions and processes among twenty-first century IOs. Of course, decentering sovereign equality does not mean that the international system should celebrate or enshrine legal inequality. Rather, the international community should develop other concepts that incorporate the notions of inclusiveness and egalitarianism associated with sovereign equality, but that are more applicable to the actions of twenty-first century IOs.