The article is devoted to studying the features of self-organization of social systems and its structural and dynamic characteristics in the context of the post-non-classical paradigm. Key attention is paid to the analysis of the openness of social systems as the most important prerequisite for their self-organization. In this regard, the phenomenon of vitality is proposed as a structural and dynamic component of self-organization, on the basis of which the role of a person in this process as an “observer-participant” is specified, due to the circumstances of human life. Further directions of social self-organization research are suggested.