The relevance of the topic is due to the pronounced weakness of the influence of small and medium-sized enterprises (SMEs) on the spatial development of the country. The purpose of the article is to advance in the systematization of the functions of SMEs in the spatial development of our country, to systematize the causes of weakness in the implementation of these functions. The most important of the reasons is due to the fact that the system of SME support created in Russia is inadequate to the needs of this sphere. This is confirmed by the fact that in a number of Russian regions, and in the country as a whole, since 2017, there has been a decrease in the number of people employed both in small (the main group of SME employment) and in medium-sized businesses. The decline is taking place against the background of a significant increase in financial volumes and an expansion of the organizational diversity of support for SMEs. The novelty of the article is the advancement in the systematization of assessments of the implementation of the potential functions of SMEs in the spatial development of Russia; assessment of the spatial dynamics of small and medium-sized businesses in recent years in terms of employment parameters from the point of view of the ability of SMEs to really influence the development of territories; assessment of the state and effectiveness of state support for SMEs at the federal and regional levels; analysis of the relationship between the real possibilities of SMEs and the structure of the Russian economy. As the reasons for the weak influence of SMEs on the development of regions, it was noted that large monopolistic enterprises do not need cooperation with SMEs. In the process of choosing measures and directions of support for SMEs, the position of officials-actors, often irrational, dominates. In the current Russian system of fiscal federalism, regional authorities have little interest in promoting the development of SMEs on their territory.