Unipolarity has been taken for granted and remains unquestioned in the International Relations literature. This article provides the conceptual history of unipolarity by bringing an immanent critique. It shows the evolution of unipolarity literature in the absence of counterbalancing in four stages. It focuses on the use of history in structural realism and brings a historical sociological perspective to the literature to show how tempocentric theorizing impaired the understanding of unipolarity as a distinct structure. The article concludes by underlying the importance of noticing the cost of reification of concepts for theorizing and by highlighting that unipolarity is still understudied both theoretically and methodologically.