One of the historical and theoretical prerequisites for P.Ya. Galperin's stage-by-stage mental actions and notions formation theory presents L. S. Vygotsky's higher psychic functions origin and nature theory. P.Ya. Galperin's personal archive and published works analysis brings us to some conclusions. First of all, L. S. Vygotsky's cultural and historical conception and Galperin's stage-by-stage mental actions and no-tions formation theory share alike methodological approach to understand human psyche of both social and historical nature, which brought forth their continuity. In the second place, P.Ya. Galperin's attitude, which is a creative development of L. S. Vygotsky's conception, presents an independent psychological theory. P.Ya. Galperin elaborated the subject-matter and method of psychology, developed the main points of psychological, monitored formation of mental actions with given properties, made up specific psychological action doctrine, three types of learning. In the third place, P.Ya. Galperin conception and that of L. S. Vygotsky's complement each other in terms of various and different psychic analysis. Our comparison of the two psychological conceptions made enables us to state their partial coincidence with their being complementary in teaching approach and its role in psychic development.