Information on age and nature of the onset of autism and other developmental disorders was obtained through review of parent completed developmental history; in addition information on the child's early development, diagnostic information, and information on parent characteristics was also obtained. In this relatively large series of cases the parents of children with autism were more likely than parents of children with other developmental disorders to report possible loss of developmental skills. However, the question of actual skill loss was complicated since in some cases parents also had reported even earlier developmental delays or a pattern more of developmental stagnation than clear loss of abilities. Only a few children exhibited a clear and unequivocal loss of developmental skills.