Effects of early intervention on intellectual and academic achievement: a follow-up study of children from low-income families.

Follow-up data, obtained 4-7 years after intervention ended, are presented for the Carolina Abecedarian Project, an experimental study of early childhood educational intervention for children from poverty families. Subjects were randomly assigned to 1 of 4 intervention conditions: educational treatment from infancy through 3 years in public school (up to age 8); preschool treatment only (infancy to age 5); primary school treatment only (age 5-8 years), or an untreated control group. Positive effects of preschool treatment on intellectual development and academic achievement were maintained through age 12. School-age treatment alone was less effective. Results generally supported an intensity hypothesis in that scores on cognitive and academic achievement measures increased as duration of treatment increased.