Theories of international relations that explain the international system and interstate relations through the formulation of anarchy have encountered a significant challenge in recent years. The hierarchy theory, the proge- nitor of this challenge, posits that international relations and world politics are governed by a composite framework in which hierarchy and anarchy coexist. Prior to World War II, official hierarchical institutions in the form of colonies and empires dominated the international arena. Since the end of the war, however, informal hierarchies in which large powers indirectly control the sovereignty of minor states have become commonplace. Based on these arguments, hierarchy theory has developed the concept of relational authority in order to reveal the appearance, nature, and effects of hierarchy on world politics and political actors. It explores the fundamental arguments of the institutional hierarchy theory, outlining its three most compelling strengths and five main drawbacks.