Social disparities emerge rather early in development and are well documented when children are three years of age. The present chapter focuses on their early roots and emergence using data of a German large-scale infant cohort study (first assessment wave) when children were about six to eight months of age. Drawing on a bio-ecological model of child development, the chapter reports on analyses of social disparities in the home-learning environment, i.e. the quality of mother’s interaction behaviour, on the one hand, and social disparities in various indicators of early child development (e.g. sensorimotor development, information processing, child characteristics in mother–child interaction) on the other. As expected the child’s and mother’s behaviour in mother–child interaction proved to be highly interrelated; however, social disparities were mainly observable in the mother’s behaviour and hardly any in early child development.