We examine how children aged zero to 6 years with migration background and those who live with lone parents, or on low income or social assistance differ from other less disadvantaged groups in their use of formal ECEC services and non-formal education activities. Previous studies have shown that attendance rates are lower for children in some of these groups, who might benefit disproportionately from high-quality ECEC services. We contribute to this literature by providing a more differentiated analysis separately for children of different ages in East and West Germany, respectively. Furthermore, we examine to what extent supply and demand side explanations may account for the observed disparities in ECEC attendance between disadvantaged groups and other children. We also draw on reasons given by mothers for their under 3 year old children's non-attendance of ECEC institutions. The empirical analysis is based on the 2010 wave of the German Socio-Economic Panel (SOEP) and the Families in Germany Study (FID). The results suggest substantially lower attendance rates of formal and non-formal education activities among children under three with migration background and for those from low income families. For children over three, social disparities in formal ECEC attendance are rather small, whereas they remain considerable in non-formal education participation for children of lone parents in East Germany and for children of low income or social assistance receiving families in West Germany. (author abstract)