It is the activity whose performance determines the formation of the main psychological developments of a person at a certain stage of his personality development. Within the notable activity other types of activities are prepared, emerged and distinguished (A. Leontiev, D. Elkonin). There is correspondence between the stage of psychological development and a certain type of L. A. The importance of L. A. for psychological development depends primarily on its content, of the aspects of reality that the person discovers and assimilates in the process of its implementation. The following types of L. A. are distinguished: 1) direct communication of the infant with adults; 2) the activity of manipulating things, which is characteristic of early childhood, in which the child understands historically sophisticated ways of interacting with specific objects; 3) playing narrative roles characteristic of preschool age; 4) educational activity of younger school children. In adolescence: communication with peers (D. Elkonin, T. Dragunova), socially useful (positive) activity (D. Feldshtein, V. Davydov), self-determination, role experience, activity of reference importance, etc. At each stage of childhood, L. A. undergoes a certain course of formation. They are formed under the guidance of adults in the process of breeding. At the same time, the emergence of a new L. A. does not mean the abolition of those that prevailed in the previous stage. Each period of psychological development is characterized by a unique system of different types of activities, but in this complex system, L. A. occupies a special place, where the appearance of fundamental changes in psychological development is determined at each stage separately.