This study investigated the school adjustment of 1,300 low-income, minority children in the Chicago Public Schools. Chidren's progress from preschool to fourth grade was traced. Data were collected from teachers, parents, children, and computerized records. The study primarily examined mediated effects of preschool; influences on cognitive growth in reading; and predictors of writing development. Results indicated that children's reading achievement declined over time, and this decline coincided with the cessation of government-funded programs and the increasing prevalence of grade retention and school mobility. Positive long-term effects of preschool programs were retention and school mobility. These effects were more likely to occur if children entered school well-prepared and if their parents were involved in their schooling. Predictors of cognitive growth included grade retention, self-perception of school competence, and parent involvement. Writing development was weakly correlated with reading achievement. Implications for improving children's school success include: (1) early reinforcement of the effects of preschool; (2) responsiveness to the problems of at-risk children; (3) enhancement of family-school relations; and (4) increased provision of writing instruction. Extensive references follow each section of the report. (BC)