In the context of a high degree of uncertainty in the modern global economic space, the search for ways that can ensure long-term stable development of the economy of the country’s regions becomes relevant. The purpose of the study is to identify the strength of relationship between the level of development of an economic entity and the degree of diversification of its economy, which will allow the regions of the Russian Federation to justify the choice of diversification or specialization policy. The level of diversification was determined by such methods as analysis of the structure of the regional economy, highlighting the sectors of the national economy that make the greatest contribution to the gross regional product; study of the distribution of employees by types of economic activity; calculation of indicators characterizing the concentration of production in territories – the Herfindahl–Hirschman index, dispersion indicator, entropy coefficient. The study identified that more than 12 % of regions have a low diversification level, mainly associated with mining operations. The author calculated the correlation coefficient between the Herfindahl–Hirschman index and the indicators of the gross regional product of the Russian Federation constituents, which allowed concluding on the absence of connection between these indicators. The author believes that diversification of the region’s economy does not guarantee an increase in its efficiency. Constituents with a low diversification level often have high indicators of socio-economic development; therefore, the focus on diversification is not always an economically sound strategy for the development of the region. Thus, increasing the diversification level does not have a direct connection confirmed by calculations with the level of development of the region; however, additional research on the structure of manufacturing industries and determining their impact on the economic system are necessary.