The field of international law is increasingly turning upon itself. For instance, there is heightened attention to its histories, to the background of the field's actors, or to the structure of international legal argument. This introduction to the concept and practice of reflexivity uses reflexivity to connect and explain these different strands of scholarship in international law. It suggests, in sum, that the field of international law is becoming more reflexive. To substantiate this view, this introduction defines the concept of reflexivity and identifies three levels of reflexive practice in the field. These levels involve turning upon (1) one’s own personal and professional situation or that of the international lawyer; (2) the situation of the field of international law; and (3) the scholarly endeavor in international law. After having situated the concept and practice of reflexivity in international legal scholarship, this introduction extracts some of the implications of its practice and highlights both its benefits and potential pitfalls. It concludes by noting that a reflexive practice may serve as a tool for international lawyers to cultivate an awareness of the contexts and constraints of the field in which they operate, and their position within it