The research deals with the issue of the development of prosociality as a unique personality trait, which ensures the person's readiness to act for the benefit of the Others in accordance with their needs, intentions and emotional states. The author summarizes the international experience with studying the essence of prosociality and its age-related development. It is pointed out that there are two basic areas of investigating the prosocial tendencies in а foreign psychological science. The first one is presented with the research concentrated on the study of prosocial behavior and another one is associated with the analysis of the development and functioning of its dispositional basis – prosociality. In the field of Ukrainian psychology this research area has not received enough exploratory attention. Certain aspects of this phenomenon are considered in the field of related psychological and pedagogical issues: personality moral development; age-related genesis of altruism or empathy, etc. It is noted that the particular attention to the ontogenetic aspect of prosociality had emerged in recent decades. The author makes the first attempt to discuss the location of prosociality as personality trait and describes the conceptual model of the age-related genesis of this phenomenon. Prosociality is considered as a biosociopsychic construct which exists on the intersection of three intrapsychic spheres, such as personality, cognitive sphere and identity. Its structure includes the inner core components and peripheral one. Inner core combines a prosocial identity, cognitive, emotional and motivational components. The peripheral part is represented by a behavioral component, which serves as an indicator of the evolution of this personality trait. The empirical study based on the 25 age-related comparative cross-sections made it possible to monitor the features of the developmental trajectory of human prosociality from early childhood to late maturity (2-65 years old). The author considers the age-related genesis of personality prosociality as a lifetime evolution of the personal trait, expressed in a large diversity of developmental changes (separation and harmonization of the principal components; changes in its hierarchical structure and the transformation of dominant components) due to the shifts of the determinants and mechanisms that cause the varying levels and the features of prosocial activity. This idea is implemented in the author’s six-stage model of the genesis of personality prosociality. It is noted that the ontogenetic development of prosociality involves two types of changes: the expansion of the structure of the phenomenon due to the inclusion of new components and the shifts in its hierarchical structure: from the primary domination of the emotional sphere to the decisive role of the cognitive one, and, eventually, to the consolidation of the dominant positions of the motivational component, which, in turn, is undergoing the phased evolution itself. Being in the mutually determined relationships with the prosocial identity, this component as the base of prosocial orientation defines the features of person’s prosocial behavior. Besides that the particular attention is paid to examining the relationships between the personality prosociality and the other intrapsychic systems: volitional control, cognitive skills, social responsibility, egoistic motivation etc. It is proved that initiativity and the level of cognitive skills determine the features of prosocial tendencies in the preschool- and at the beginning of elementary – school age, but further they lose their dominant position. As a holistic construct, personality prosociality is built up to the end of adolescence. Since the next age period, personality prosociality functions on the one of three levels: the inert prosociality, the mature prosociality, and altruism. Discussing the relationships between.
