The paper studies the evolution of the research of the Russian middle class. The middle class is considered as part of the social structure, providing its effective functioning. It reveals the most significant characteristics of the formation and development of the Russian middle class. Also, there is shown the special role of the middle class as the main factor ensuring the stable development of society. The analysis allowed to generalize the scientific experience of studying the Russian middle class, and draw some conclusions related to the realities of the Moldovan middle class.