What does it mean to mediate in the contemporary world? During the Cold War, and since, various forms of international intervention have maintained a fragile strategic and territorially sovereign balance between states and their elite leaders, as in Cyprus or the Middle East, or built new states and inculcated new norms. In the post-Cold War era intervention and mediation shifted beyond the balance of power and towards the liberal peace, as in Bosnia-Herzegovina, Kosovo, and Timor Leste. In the case of Northern Ireland, identity, territorial sovereignty, and the nature of governance also began to be mediated, leading to hints of complex, post-liberal formulations. This article offers and evaluates a genealogy of the evolution of international mediation.