This report describes the history, program, sample population, assessment methods, participant reactions, and final evaluation of a 7-year study which investigated the long-term effects of a 2-year traditional nursery school intervention program. A total of 30 disadvantaged children with below-normal initial IQs began the full-day program at age 3 and continued the program for 2 years. The children then entered a special kindergarten class for one year, were kept together for 2 subsequent years in a special school situation, and entered regular third grade classes. Followup information was obtained during the third, fourth, and fifth grades. The assessment criteria used were restricted to objective measures of intelligence and school achievement, such as language use and understanding, perceptual discrimination, concept formation, sensorimotor coordination, memory, and number skills. Final results indicate that the improvements evidenced by children in the treatment group after the preschool program gave them little or no advantage by the end of the fourth grade over their peers who did not receive treatment. Sex, initial IQ, and sociometric status showed systematic relations to patterns of later IQ scores and school achievement measures. Methods of assessment used and final results are discussed in detail. (ED)