The article examines the concept of gratitude, cites key aspects of its awareness as an attitude, experience and dispositional trait. The approaches of E. Diener, M. Seligman, underlying positive psychology, are chosen as the starting point for defining gratitude as a phenomenon. It is emphasized that gratitude as a phenomenon is of great importance for study because its experience is connected with the state of personal mental health. The work contains the results of psychological studies, which investigate the relationship between gratitude and the subjective and psychological well-being of the individual. The researches revealing the correlation of gratitude and experienced emotional states of a personality, its social connections are considered. According to the arti-cle, the presented analysis of the studies can serve as a basis for hypothesis formation with the purpose of their subsequent empirical testing as a part of domestic psychological research of the personality's gratitude phe-nomenon.