The Perry Preschool Study was a longitudinal study of the impact of the Perry Preschool (Ypsilanti, Mich.) experience on the subsequent behavior and school achievement of 123 poor black youths born each year from 1958 to 1962. Each wave was divided into experimentals and controls. The controls did not participate in a preschool program. Subjects were traced through age 19. Compared to the controls, the experimentals were significantly more likely to have performed well in school and remained free of delinquency. In the Syracuse University study, experimental children participated in a day care program for their first 5 years while the control group did not. Probation and court records were examined when subjects were 13-16 years old. Only 6 percent of the experimentals had been placed on probation compared to 22 percent of the control group. The High/Scope Preschool Curriculum Comparison study indicated that preschool curriculum models may differ radically in their effects on juvenile delinquency. This and similar studies indicate that the most effective preschool programs have a staff with early childhood training and a curriculum focus, use a validated curriculum model that permits children to plan or choose their activities, have support systems to maintain the curriculum model, have a 1.8 staff-pupil ratio, and structure collaboration between staff and parents. 34 references.