This study — perhaps the most well-known of all High/Scope research efforts — examines the lives of 123 African Americans born in poverty and at high risk of failing in school.
From 1962–1967, at ages 3 and 4, the subjects were randomly divided into a program group that received a high-quality preschool program based on High/Scope's participatory learning approach and a comparison group who received no preschool program. In the study's most recent phase, 97% of the study participants still living were interviewed at age 40. Additional data were gathered from the subjects' school, social services, and arrest records.
The study found that adults at age 40 who had the preschool program had higher earnings, were more likely to hold a job, had committed fewer crimes, and were more likely to have graduated from high school than adults who did not have preschool.
Lawrence J Schweinhart, Jeanne Montie, Zongping Xiang, William S Barnett, et al.. Lifetime effects: The High/Scope Perry Preschool study through age 40. Ypsilanti(2005)
Available at: http://works.bepress.com/william_barnett/3/