This Institute for Developmental Studies (IDS) program was established in 1958, and represented an attempt to study the inter-play of environment on psychological development, and to evolve and develop an enriched and stimulating school curriculum for socially disadvantaged children. Over the years, the IDS program has evolved into a comprehensive five year enrichment curriculum, running from the kindergarten year through the third grade. The academic progress of both Institute and control children was monitored over the five year period by administering both standardized and Institute-developed tests and observational procedures. IDS experimental children and those in the control groups were tested with a wide battery of measures of ability and achievement. Longitudinal evaluative information was obtained through the administration of the Stanford-Binet Intelligence Scale (Form L-M), the Peabody Picture Vocabulary Test, the Illinois Test of Psycholinguistic Abilities, the Lorge-Thorndike Intelligence Tests, and the Metropolitan Achievement Tests. The findings reviewed in this report show a positive change for children who experienced five years of enrichment in the Institute for Developmental Studies program, as compared with a control group of children who were not in the enrichment program. Experimental children performed better on a number of measures of ability and achievement, and appeared to maintain much of their early enrichment advantage over their controls. (Author)