The perceptions of parents of 113 developmentally delayed preschool children were compared with mental ages derived from the Cattell Infant Intelligence Scale and the Stanford Binet Intelligence Scale. With the parents as informants, an Alpern-Boll Developmental Profile was completed. Findings demonstrated a high degree of correlation between the child's test performance and the parents' estimate. Correlations indicated that parents were slightly more accurate in estimating the functioning level of an only child and the middle child, the older rather than the younger child, and the moderately and mildly retarded rather than the severely and profoundly retarded. Findings suggested that parents' awareness can be used to help professionals in evaluation. (CL)