The article deals with the problems of defining middle classes. Theoretical principles of social and class structures, including middle classes, are examined. The criteria of reckoning some hired workers as middle classes worked out on the basis of normative methodology (normative criteria) are submitted, the most important of them being educational qualifications, occupation, personal income and provision of housing. Methods of statistical and sociologic analysing data are applied. The results of analysing the conformity of the hired workers to the normative criteria of representing middle classes are produced. It is determined that today heads of organizations and their subdivisions as well as certified top and middle management specialists representing middle classes comprise only 2-3 per cent of the total number of the hired workers. It should be noted that there are practically no-one among them who has got a family with two and more children. The low level of wages is the main reason for that. In addition there are some other reasons, too. The results of the research could find application in the state social and economic policy.