The author considers the problem of interdepartmental interaction of governmental social organisations in a territorial community of a city. The purpose of the article: to identify the main barriers of interagency interaction in the process of prevention of social orphanhood. Methods of research used: theoretical knowledge − analysis, synthesis, systematization, classification, generalization to find out the content of the basic concepts of research, substantiation of the essence of interagency interaction in the process of prevention of social orphanhood; empirical: diagnostic (survey methods − questionnaires, focus groups), socio-pedagogical experiment and monitoring to study the state of the problem under study; statistical (quantitative and qualitative data processing with the help of mathematical statistics for comparison and confirmation of the obtained results of research). Main principles of interdepartmental interaction and interdepartmental barriers have been defined, which may complicate such interaction. The author proposes ways of coping with interdepartmental barriers on the basis of social partnership and involving non-governmental organisations into coworking with territorial governmental agencies. The model of interdepartmental interaction of territorial community subjects as a practical mechanism of realisation of social orphanhood prevention on the basis of systematical approach has been proposed. Also the author justifies the importance of interdepartmental partnership of governmental and non-governmental social institutions concerning social orphanhood prevention at the stage of coping with family discomfort in terms of a territorial community of a city. Ways, forms and methods of involving and activation of territorial community subjects into preventional work with vulnerable families for prevention of social orphanhood have been provided.