Why and how does the politics of identity lead to contestation in international orders? I argue that international actors engage in social positioning, which is to say that they are continually engaged in political moves that both enact and alter collective beliefs about social categories and the deeper understandings on which they are based. This background knowledge produces both hierarchies in international politics, and the institutions and practices that define international orders. By examining struggles over social positioning, which enables the competent performance of identities, I aim to shed light on how social positioning affects the reproduction and evolution of international orders. Political conflicts, from diplomatic quarrels to hegemonic wars, may thus be seen as struggles to assert relational position, and to enact particular practices as the proper “way things are done” in world politics. The generalizability of an identity performance approach is illustrated through case studies spanning different regions and issue areas of international relations. The cases include the change to practices of sovereignty and intervention that were enacted through the human security agenda. I examine the ideational challenge presented by the rise in ethnic conflicts in the 1990s and the efforts by the UN Secretariat and Canada to enact the Responsibility to Protect doctrine, which formalized a shift in which previously taboo intervention was now permissible in cases of mass atrocities. It then examines the post-Cold War rivalry between Russia and the US to enact their identities and extract recognition as a great power and hegemon, respectively, which has degraded the international security order. In international political economy, it studies how the Eurozone debt crisis in Greece was defined by clashes between the “ordoliberalism” of creditor states and EU institutions, the International Monetary Fund’s attempts to assert its identity as the preeminent site of international economic expertise, and Greece’s identity-driven imperative to maintain social position inside the European core.