In the article content foundations of the development of international relations of the European Union in the field of non-formal education of children and studying youth are revealed by using a group of scientific methods, as well as the method of systemic structural analysis. The author focused on the modern European trend of mainstreaming non-formal education as a possibility of socialization of the younger generation through participation in non-formal educational activities. The value of fundamental scientific research of foreign scientists on the problem of development of non-formal education as lifelong learning and the development of international cooperation in this sphere is underlined in the article. The relevance of scientific discussion of this problem in native and foreign science been confirmed by the analysis of a wide range of educational research. The value of cross-sectoral approach in shaping of content foundations of international cooperation the EU in informal education is underlined in the article. Therefore, the interaction of education, youth and social policy is based on the presented study. In the article the author describes the main content direction of the international cooperation in the field of non-formal education of children and youth, defines the basic forms of realization of content of this process. The main forms of realization of substantial directions of international cooperation in this field are systematized by the author of the article that based on the analysis of a wide range of information sources. The prospects for the further research in view of the development of the implementation (content and form) and interconnection of each of the directions of international cooperation EU non-formal education children and youth are defined.