Proceedings of this Round table reveal the role and significance of M. Ostrogorski’s theoretical heritage for the history and contemporary development of political science. Importance of the development of political sciences at St. Petersburg University in the 1870s for the formation of M. Ostrogorski as a poliical researcher is demonstrated, peculiarities of the scientist’s worldview in the context of Russian and foreign constitutionalism and parliamentarism are disclosed; the critical nature of his democratic theory and political parties theory, today’s relevance of his study of women’s issues and of other topics are shown.