The modern development of civil society is directly related to the effective activity of civil society institutions. At the same time, their activities have attracted more attention from political scientists, philosophers, government officials, than educators. The analysis of the activities of such institutes showed their increase in the pace of development and the variety of implemented tools and technologies in youth work. Thus, considering the relevance of the current trends in the development of Ukrainian civil society in the identification of the key role of a number of civil society institutions that have a weighty impact on youth, conducting a theoretical analysis and content-based presentation of the system of formation of youth social activity in the institutions of civil society. The purpose of the study is to substantiate and highlight the component composition of the system of formation of youth social activity. The allocation of component composition was based on the theoretical background of specialists in the field of social work, as well as the personal experience of the author in the public sector and in working with young people. The institutes of civil society that influence the formation and development of social activity of youth include the following: public organizations, youth centers, youth councils, charitable foundations. The theoretical analysis of the problem under the research problem provided an opportunity for defining the system of formation of youth social activity in the institutions of civil society as a holistic process, which includes a set of interrelated and interdependent components, in particular, purpose, object and subject, content, directions, forms and methods of working with youth in civil society institutions. The research system is represented five substantiated structural components: target (goal, task, principles, result), subject-object (subject and object of research), substantive (directions, content of activity of civil society institutions), procedural activity (forms and methods of youth work), environmental (conditions of formation of youth social activity).