International administrations are still being considered as a solution to many difficult conflicts globally. This book develops a new understanding of sovereignty, focusing on how international officials make claims to rule. Nicolas Lemay-Hébert argues that sovereignty is best understood as a set of practices, more precisely struggles between actors vying to assert their political authority and another set of actors striving to keep this political authority under check. This book examines all the cases of international administrations by the League of Nations and the United Nations, focusing on how international officials have made claims to assert their political authority over specific territories and populations. It also reviews all the accountability demands expressed by local actors and how these demands shape the future practices of international administrations.