As an actor involved in sociologizing the study of international relations in France, Yves Dezalay has made a major contribution by offering keys for the sociological analysis of imperialism. In order to understand the importance of his research, it is first necessary to resituate it in relation to the Marxist and transnationalist analyses that were dominant when he began his work. Yves Dezalay’s originality notably lies in his close attention to elite trajectories and his refusal to essentialize international organizations and social classes; in his consideration of structural differences, both material and ideological, between the fields of power; and in his emphasis on the double agent, seen as the linchpin of imperial domination. Despite never claiming to do so, Yves Dezalay’s work, through its sociological rigor, contributes to the renewal of international relations theories on a question that sociology tends to carefully avoid: that of imperialism.