Interregional interaction is one of the most important areas of regional state policy. Such a policy is based on the principles of mutual benefit and on achieving the highest possible socio-economic effect for each subject of relations. In modern reality, territorial interaction means constantly developing the mechanisms of inter-regional integration, improving the economic division of labor between the subjects of the Russian Federation, improving the performance of the industrial sector, projects in the field of trade and communications. Optimization and diversification of intersubjective interactions are aimed at qualitative growth of the well-being of the population, strengthening the integrity of the territories and their economic security. In practice, different structures are created within the framework of inter-regional relations to promote the development of different forms of integration processes. One of the most popular forms are inter-regional associations of economic interaction. At the same time, analysis is not limited to the single given territorial entity. We are convinced that inter-regional interaction is the driving force of both the national and the global economies. The weakening ties between regions, on the contrary, lead to a decrease in the production potential, loss of the competitive potential of economies, and slowdown in economic growth. The study examines the issue of intersubject interaction as one of the key areas of regional state policy. We have considered the system of inter-regional interactions through analysis of its individual elements: regulatory framework, territorial entities, modern tools for organizing interaction. The study yielded the following results: we have identified the main problems in the functioning of the modern system of inter-regional interactions; we have defined the main stages and trends in Russian legislation regarding inter-regional cooperation; we have identified territorial entities of interregional interaction and also the key issues in their activities based on the study of the regulatory framework, information from corporate sites, scientific publications, mass-media materials; we have used the obtained data to identify and analyze the main tools of inter-regional cooperation: programs of socio-economic development; investment programs; concepts of interregional relations; interregional agreements between subjects of the Russian Federation; concepts of cross-border cooperation in the Russian Federation; we have also focused on the problematic aspects of their application.