This article analyzes the socio-economic factors causing disparities in the level of health of preschool children. Using data from the Russian Longitudinal Monitoring Survey of the Economic Situation and Health of the Population of the NRU HSE, it demonstrates that a mother’s health and lifestyle determine her child’s health. It does not find a significant connection between a child’s health and indicators of a family’s financial well-being, level of the mother’s education, her age, or her employment or marital status. The results obtained are substantially different from factors that determine children’s health in developed countries. This is probably because in Russia, various income groups have similar behavior patterns, access to quality medical care, attitudes toward health, and harmful habits.