The paper is dedicated to the 115th birthday of P.Ya.Galperin, the classic of national psychology (1902-2017). The purpose of the paper is to showP.Ya.Galperin’s contribution to fundamental and practiceoriented science, and alsoto revealthe link between these two approaches sides in his scientific heritage. The gist of his innovative psychological theory is disclosed. The key methodological principlesare highlighted: understanding of the scope and method of psychological science; psychophysical issue, i.e. the nature of psyche and the mental world; a psychophysiological problem, the issue of the relationship between psychology and physiology; the issue of human instincts in connection with historical social nature of consciousness; the notion of linguistic consciousness and the relation of language and thought; the principle of unity of history and theory in scientific knowledge. Terminological work carried out by P. Ya.Galperin is analyzed. The introduction of new concepts enriches and makes the conceptual apparatus of psychological sciencemore precise. The necessity to reveal each methodological provision to solve practical problemsis mentioned. The unity of theoretical and practical aspects in psychological theory developed by P. Ya. Galperin, its authentic nature and relation to the culturalhistorical psychology of L.S.Vygotsky, activity concepts of S.L. Rubinstein and A.N. Leontiev are shown. There are several directions in which the method of gradual development of mental functions and concepts organizes the process of teaching and learning, the mechanisms of perceptionand simultaneous mental processes, the phenomena of Jean Piaget are explained. To sum up, the inexhaustible possibilities of the practical use of the theory of P.Ya. Galperin in all areas of individual experience.

The paper contains the description of Pyotr Ya. Galperin’s scientific biography stages. P.Ya. Galperin (1902–1988) is an outstanding Russian psychologist, the founder of an original psychological concept. The paper shows how P.Ya. Galperin’s scientific views were logically developing when he was working on the theory of gradual development of human intellectual activity that analyzes the process of constructing basic components of mental activity and creates the conditions for transforming the action into a psychological phenomenon.

The biography is compiled on the basis of publications and talks of P.Ya. Galperin, the memories of colleagues and friends, using numerous archives. By now, only the main events in the life of a scientist have been marked. The paper presents the data that could be verified by referring to P.Yа. Galperin’s CV and data of the Academic Council of the Faculty of Psychology, Lomonosov Moscow State University, stored in the Archive of Lomonosov Moscow State University, and P.Yа. Galperin’s science archive passed by the grandson Yakov I. Abramson to the Archive of the Institute of Psychology of the Russian Academy of Sciences. The family archives failed to survive because of the frequent relocation, and P.Ya. Galperin did not write a detailed autobiography, so the task of clarifying the facts of his biography is relevant.

All periods of P.Ya. Galperin’s scientific creative life are presented, his participation in scientific and practical events starting with the mid-1920s is mentioned. The 1930- 1940s are the most difficult years for event recovery. 55 years of professional and personal life (from 1943 and until his death in 1988) are associated with Lomonosov Moscow State University, therefore the focus is on P.Ya. Galperin as an outstanding Professor of Moscow University, i.e. the author of the original theory of the orientating nature and function of human mind, the organizing force in psychology. 

The conclusion highlights how the modern scholars are preserving the scientific heritage of P.Ya. Galperin.