The article deals with some ideas postulated by Jozef Obrebski, making reference to the opinions of his contemporary Polish scholars on the one hand, and on the other hand to fashionable ideas well-known in sociology and anthropology among some Western scholars today. The latter have now rediscovered the perspective which some fifty years ago was already well established in Polish sociology and ethnology, where, for a number of reasons, questions of the nation and ethnicity have always occupied an important place. Some Polish sociologists have, for a long time, used research methods and concepts which are in fact specific for anthropology. Polish sociology thus offers many research methods and interpretations which in the West belong to anthropology. Obrebski deserves particular attention, by virtue of his inspiring and original combination of interest and experience as an ethnologist and sociologist. He defines the ethnic group as an imagined community, existing in the community consciousness, marked by unique relations with respect to ethnic identity. His approach to ethnicity can be linked and compared to the much later views of Fredric Barth.