This book presents a case for a basic reorientation of International Relations away from the state and towards the study of social institutions in the sense of patterned practices, ideas and norms/rules. IR has always suffered from a parochial occupation with the state and the Western system of state. Its main theories revolve around these phenomena, and have resulted in the reification of the state: it has been turned into an essential actor, with certain immutable and fundamental properties that remain constant throughout time. A list of these properties usually includes territorial limits, centralisation, monopolisation of violence and exclusive loyalties. International Institutions in World History shows how the state is an inherently modern phenomenon, a modern social institution, and that foundational concepts in IR should be based on a full appreciation of the wider record of human existence on earth, trans-historically and cross-culturally. Schouenborg argues that these social institutions may be captured via a universal functional typology consisting of four categories: legitimacy and membership; regulating conflicts; trade; and governance. The book will be of interest to scholars and students within IR (particularly IR theory), anthropology, archaeology and sociology, and those interested in general social theory.