The purpose of this article is to seek an answer to the question about the theoretical and methodological identity of the science of international relations. The discussion on this topic started in Poland and in the world after World War II. In 1947, Ludwik Ehrlich wrote that the science of international relations deals with the broadest kind of the coexistence of people – the coexistence of the entire mankind, the ‘coexistence of nations’. Remigiusz Bierzanek, in turn, wrote in 1971 that the scientific discipline of international relations had emerged in a synthetic manner rather than as a result of the division of any pre-existing broader discipline. Thus, he was the first scholar in Poland to point out the multi- and interdisciplinary character of this discipline. The article is based on the assumption that the attributes of the disciplinary character of the science of international relations can be identified on the basis of ontological, epistemological and methodological criteria. In the ontological perspective, the categories of ‘sovereignty’ and ‘internationality’ as well as dis tinguishing the levels of analysis make it possible to define the subject and scope of research of international relations. In the epistemological perspective, it is characterised by having its own theories and a rich tradition of theorizing. The science of international relations has its own specific methodology adjusted to the subject of research. It also has its own history and historiography, which are important for furthering the development of the discipline’s identity and the theoretical and methodological self-awareness of the scholars conducting research in this discipline.