This introductory chapter provides an overview of the institutionalization of world politics demonstrating the continuing close relationship between international institutions and power politics. We propose new and innovative definitions of international institutions and power politics and unpack how our definitions relate to these concepts as usually understood in the study of international relations. The volume’s attempts to understand the relationship between international institutions and power politics are situated in the study of international relations, and we specify how we add to the current research agenda. We identify the major research questions of the volume and briefly introduce the chapters to follow. Finally, we address the significance of this volume and set out a future research agenda.