This chapter concentrates on the conditions of access to and the nature of membership in the international system as established by international law—specifically, three issues. The first issue is the type of society that is presented as a legitimate collective member of the international order. One of the first steps that international law takes to determine legitimacy at the international level is to identify the criteria necessary for a collective actor to be viewed as a full-fledged legitimate member of the international community. The second issue is that after World War II and the creation of the United Nations (UN), access to international membership in the international order moved toward a form of universality that has been relatively pluralistic. The third issue is that despite this movement toward a pluralistic universality, there are limits to the universality and pluralism of international membership in the international system as defined by international law.