The Perry Preschool Project assessed longitudinal effects of a 2-year program consisting of a daily 3-hour cognitively oriented nursery, a weekly 90-minute home visit, and less frequent group meetings of the pupils' parents. Subjects consisted of 3- and 4-year-old Negro disadvantaged and functionally retarded children, whose pretest scores on the Stanford Binet Intelligence Scale were not above 85. The program operated from September 1962 until June 1966. About 24 children took part each year. Upon entering, the children were pretested on the Stanford-Binet, the Peabody Picture Vocabulary Test, and the Leiter International Performance Scale. These and other tests were used later in the program. Few significant differences between experimentals and controls were noted on the pretests. The California Achievement Tests in reading, language, and mathematics were given at the end of the first grade and again at the end of the second grade. The results showed significant gains for the experimentals over the controls. (JS)