The historical approach and main points of view in the works of A. N. Leontjev are presented, It is aimed at solving problems of the foundation and integration of the science of psychology by means of a specification of dialectical and historical thinking in Marxism to the object of psychology. On this basis Leontjev proposes an objective definition of mental phenomena and elaborates it within the historically developing unity of subject-activity-object. Psychological processes are seen as subjective means mediating the activity of the individual in securing survival and enabling development in the direction of self-determination. The human personality is grasped as a formation arising in the course of individual development and necessitated through changes in the social unity of subject-activity-object. This enables a specification of the concept of personality through a determination of its specific function in this unity. Thus the specifity of the concepts of the humane, the individual, the individuality, the subject, and the personality can be determined and so an essential contribution to the clarification of basic problems in the theory of personality be given.