The High/Scope Perry Preschool study is a scientific experiment that has identified both the short- and long-term effects of a high- quality preschool education program for young children living in poverty. From 1962 through 1967, David Weikart and his colleagues in the Ypsilanti, Michigan, school district operated the High/Scope Perry Preschool Program for young children to help them avoid school failure and related problems. They identified a sample of 123 low-income African-American children who were assessed to be at high risk of school failure and randomly assigned 58 of them to a program group that received a high-quality preschool program at ages 3 and 4 and 65 to another group that received no preschool program. Because of the random assignment strategy, children’s preschool experience remains the best explanation for subsequent group differences in their performance over the years. Project staff collected data annually on both groups from ages 3 through 11 and again at ages 14, 15, 19, 27, and 40, with a missing data rate of only 6% across all measures. After each period of data collection, staff analyzed the information and wrote a comprehensive official report.