International legal scholarship has increasingly turned to various traditions of sociology and social thought to challenge the constraints of orthodox international legal thinking, and to develop new kinds of thinking, more suitable for the rapidly transforming social and political landscape in which contemporary international lawyering is done. This Research Handbook seeks to showcase this work, marking the present fertile period of creative borrowing between the disciplines of international law and sociology with a collection of works at its cutting edge. Each contributor to the Research Handbook situates their intervention within a particular tradition of sociological or social theoretical thinking, and then explains how and why this tradition is useful in thinking about some contemporary development, or problem, within the domain of international law and governance. This introductory chapter seeks to clear the ground for the contributions which follow, by outlining a map of some major theoretical conversations within sociology. It identifies three core approaches which are most commonly identified in sociological literature, and briefly reflects on a number of early engagements between international law and sociology (mainly the writings of Max Huber and Julius Stone). It then argues that more recent engagements between international law and social thought stem in significant part from attempts to understand the nature, dynamics, and stakes of globalization as it relates to law, and reflect the main arena in which the significance of post-structural social theory for international law continues to be negotiated and defined.