The high-risk infants who initially enrolled in the Abecedarian Project, a longitudinal prospective study of the benefits of early childhood educational intervention within a child care setting, were followed up as young adults (age 21 years). One hundred-eleven infants were in the original sample; 104 took part in the follow up. Treatment was provided in 2 phases: during preschool and in the primary grades. Participants received either both phases, 1, but not both, or neither. Assignment to groups was random. Those in the preschool treatment group earned significantly higher scores on intellectual and academic measures as young adults, attained significantly more years of total education, were more likely to attend a 4-year college, and showed a reduction in teenaged pregnancy compared with preschool controls. Preschool treatment was associated with educationally meaningful effect sizes on reading and math skills that persisted into adulthood. School-age treatment served to maintain preschool benefits for reading, but by itself, the effects were generally weaker than those of the preschool program. Statistically significant differences in the attainment of full economic independence were not found at this stage, but would not be expected among young adults still attending school. The incidence of self-reported violence and lawbreaking was not significantly reduced, although trends in the data favored the treated group. The reported incidence of marijuana use was significantly less among treated individuals. The positive findings with respect to academic skills and increased years of post-secondary education support policies favoring early childhood programs for poor children.