A program at the Model Preschool Center for Handicapped Children at the University of Washington's College of Education enrolled 11 children with Down syndrome, 18-36 months of age. The program sought to accelerate and maintain the motor and cognitive skills of the children; to encourage parent involvement; to provide training to students, teachers, and paraprofessionals; and to develop a model that could be replicated in other settings. Children in the program moved through five classes: Infant Learning, three levels of Preschool, and Kindergarten, as they became developmentally ready. A study of the impact of the special program involved two comparison groups: non-participants with Down syndrome and non-Down syndrome mentally retarded children. Data suggest that the early intervention program had a positive effect on the cognitive and behavioral development of program participants, as they achieved higher scores than comparison pupils on the Peabody Picture Vocabulary Test and the Vineland Social Maturity Scale. The gains that were made at the preschool level were maintained during a subsequent year when some of the children attended a special class at a public school. A 6-year followup study of nine former program participants showed that their general mental performance was maintained, and even accelerated in some cases. (JDD)