The article examines the middle strata in Russia at the beginning of the 20th century, gives a definition of the term. The author indicates the dual nature of the middle strata: owners and workers, managerial and creative work. The term of middle strata reflects the economic, social and professional heterogeneity of the so-called middle class. The «old» and «new» middle strata are distinguished and those groups of the population that can be attributed to them. The old (traditional) middle strata, who came from the estates of peasants and burghers, included small traders, clerks, artisans, as well as other representatives of small and medium-sized businesses. All of them, with the development of market relations and liberation from estate dependence (in particular, shop restrictions), became professional workers. Their combination of property and personal labor was obvious: property was materialized, entrepreneurs worked in their institutions, and they were engaged not only in managerial and organizational work, but also in performing work, even if they attracted a certain number of workers. The new middle strata included various categories of employees, officials, intellectuals, including women. Their appearance and numerical growth were associated with the rapid development of capitalism in the Russian Empire after the bourgeois reforms of the second half of the 19th century. The work of these persons, as a rule, was well paid and had an independent character. They also possessed intellectual property. The new middle layers outnumbered the old ones in specific gravity. The author concludes that the middle layers were characterized by numerical growth and general scarcity; uneven territorial distribution (predominance in cities); multi-layered composition (capitalist and small-scale production); social, professional and industry heterogeneity; a combination of class and estate principles. All this testified to the incompleteness of the processes of class formation in the Russian Empire at the beginning of the 20th century.