The pattern of acquisition of social, communication, and daily living skills was examined for autistic children, compared to retarded and normal controls, by quantifying intradomain scatter on the Vineland Adaptive Behavior Scales. Autistic children were matched to normal children and mentally retarded children on Vineland raw scores; group differences in scatter were examined for each domain of adaptive behavior. Autistic children had significantly more scatter on Communication and Socialization than both control groups. Item analyses showed that the autistic children had particular weaknesses on items reflecting attention to and pragmatic use of language, as well as play and reciprocal social interaction; the autistic children had particular strengths on items reflecting written language and rote language skills, and rule-governed social behavior. The number of items showing consistent group differences, however, was small, suggesting that although autistic development appears sequentially deviant and not merely delayed, individual autistic children derive their scatter from different items, and are a developmentally heterogeneous group.