The article analyzes the issue of relevance of Stanisław Ossowski’s theoretical concepts. It particularly focuses on three themes present in his writings: the attitude to Marx’s legacy, the assumptions of his non-communist socialism and relations of sociology to philosophy. It is stressed that the contemporary relevance of Stanisław Ossowski’s writings relies not only on the theoretical value of his work in many disciplines, but — above all — their interdisciplinary character. Needless to say, Ossowski still remains a moral authority for many academics specializing in humanities.