The philosophy of science and social science has played and continues to play an important role in shaping and informing the development of international relations as a field of study. It has impacted the way in which IR theorises its subject matter, legitimises knowledge and makes methodological choices. Problems raised in the philosophy of science are often described as metatheoretical. Metatheory examines the basic assumptions of theory and the way these influence different theorisations and research practices. Interest in IR metatheory becomes particularly pronounced during periods of ‘great debates’ or ‘paradigmatic debates’ within this field of academia. The aim of the article is to explore the role of metatheory in the study of international relations. The key question concerns the reasons why IR scholars are particularly interested in metatheory. I also discuss the IR understanding of theory and the history of IR metatheory, including by presenting different positions within the debate on the role of metatheory in the study of IR.