In 1982, the Maryland State Department of Education initiated a longitudinal study of its Extended Elementary Education Prekindergarten Program. The study was designed to examine the effects of early education on low-income children's later school performance. The school performances of program participants and members of a comparable nonpreschool group were analyzed when participants were 16 years of age. Major questions addressed were: (1) What effect does prekindergarten have on participants' school behavior and how does their school behavior compare with that of members of the nonpreschool group? (2) Does prekindergarten participation improve economically disadvantaged children's performance to the extent that they achieve at a level comparable to that of children from a variety of socioeconomic backgrounds? (3) If prekindergarten leads to higher achievement, are the differential effects sustained over time? and (4) Does the achievement gap between the prekindergarten and nonpreschool groups widen as members of the groups progress through school? In this phase of the study, the effects of prekindergarten were traced from kindergarten through 10th grade. Findings confirm that prekindergarten schooling helps children perform better in the early learning years and that the successful educational experience of these student appears to have a sustained long-term effect that continues through the secondary years. Appended are 24 references. (GLR)