A day treatment program was provided for 31 children (ages 2 through 6) with DSM-III diagnoses of infantile autism or pervasive developmental disorder. The main intervention strategies were use of positively charged affective experiences to aid the development of close interpersonal relationships, use of play in all its interpersonal, cognitive, and structural variety, and a pragmatics-based language therapy model delivered within a highly predictable and carefully structured milieu. Over a 6-month intervention period, subjects demonstrated significant treatment effects in cognition, perceptual/fine motor, social/emotional, and language skills, which were maintained or increased over a 12- to 18-month treatment period. Play skills increased significantly in symbolic complexity, symbolic agency, and symbolic substitutions. Additionally, there was significant reduction of autistic symptomology.