Parents' involvement in early intervention (EI) services fosters positive developmental trajectories in young children. Although EI research on parenting skills has been abundant, fewer data are available on parents' knowledge of normative child development. Sixty-seven mothers of children participating in a Midwestern city's EI program completed the Knowledge of Infant Development Inventory. Compared with mothers in normative referent samples, mothers of children enrolled in EI reported significantly less knowledge of normative child development and were significantly more likely to underestimate the timing of normative developmental milestones. The race/ethnicity of mothers of children in EI was significantly related to their milestone accuracy scores even after the mothers' education level was controlled. Implications of the findings are discussed within the context of providing EI services that are family centered.