Coalition for Evidence-Based Policy
Coalition Advisory Board

Robert Boruch
University of Pennsylvania

Jonathan Crane
Progressive Policy Institute

David Ellwood
Harvard University

Judith Gueron
Russell Sage Foundation

Ron Haskins
Brookings Institution

Robert Hoyt
Jennison Associates

Blair Hull
Matlock Capital LLC

David Kessler
University of California, San Francisco

Jerry Lee
Jerry Lee Foundation

Dan Levy
Mathematica Policy Research

Diane Ravitch
New York University

Laurie Robinson
University of Pennsylvania

Howard Rolston
Brookings Institution

Isabel Sawhill
Brookings Institution

Martin Seligman
University of Pennsylvania

Robert Slavin
Johns Hopkins University

Robert Solow
Massachusetts Institute of Technology

Nicholas Zill
Westat, Inc.

Executive Director

Jon Baron (

1301 K Street, NW
Suite 450 West
Washington, DC 20005
FAX 202-728-0422

Abecedarian Project (High-quality child care/preschool for children from disadvantaged backgrounds)

RCT shows major impact on educational and life outcomes.

Description of the intervention:  The Abecedarian Project, initiated in 1972, provided educational child care and high-quality preschool from age 0-5 to children from very disadvantaged backgrounds (most raised by single mothers with less than a high school education, reporting no earned income, 98% of whom were African-American).  The child care and preschool were provided on a full-day, year-round basis; had a low teacher-child ratio (ranging from 1:3 for infants to 1:6 for 5-year-olds); and used a systematic curriculum of “educational games” emphasizing language development and cognitive skills.  The average annual cost of the intervention was about $13,900 per child (in 2002 dollars). 

Some of the participating children also received a school-age treatment in grades 1-3, in which a home-school resource teacher served as a liaison between the child’s home and public school, and encouraged parents to work with their children each day on individualized curriculum packets.  (As noted below, this school-age component was found to have only a marginal effect on most outcomes.)

Click here to go to the program's web site.


RCT of 111 participating children, followed through 21 years of age.  The children were randomly assigned to one of four groups, in which they received:

(i) the child care/preschool treatment (age 0-5) alone;
(ii) the child care/preschool treatment (age 0-5) and the school age treatment (grades 1-3);
(iii) the school-age treatment alone;
(iv) no treatment (this group could and often did use other child care and preschool resources available in the community.)

Study Findings

At age 21, the study found that educational and life outcomes for the children receiving the child care/preschool treatment (groups (i) and (ii)) were much superior to outcomes for the children not receiving the child care/preschool (groups (iii) and (iv)).  The results are summarized below.   By contrast, the school-age treatment alone had only a marginal impact (results not summarized here).

Impact of child care/preschool on reading and math achievement, and cognitive ability, at age 21:

  • An increase of 1.8 grade levels in reading achievement
  • An increase of 1.3 grade levels in math achievement
  • A modest increase in Full-Scale IQ (4.4 points), and in Verbal IQ (4.2 points).

Impact of child care/preschool on life outcomes at age 21:

  • Completion of a half-year more of education
  • Much higher percentage enrolled in school at age 21 (42 percent vs. 20 percent)
  • Much higher percentage attended, or still attending, a 4-year college (36 percent vs. 14 percent)
  • Much higher percentage engaged in skilled jobs (47 percent vs. 27 percent)
  • Much lower percentage of teen-aged parents (26 percent vs. 45 percent)
  • The study also found suggestive evidence of a reduction in criminal activity, but because of the small sample size, most of these effects were not statistically significant.

Discussion of study quality (click here for glossary of terms)

  • The study had low attrition and a long-term follow-up:  Outcome data were collected for 94 percent of the original sample at the age-21 follow-up.
  • The study reported outcomes using an intention-to-treat analysis.
  • Standardized instruments were used to measure cognitive ability and academic achievement (the Wechsler Adult Intelligence Scale-Revised, and the Woodcock-Johnson Psychoeducational Battery-Revised).
  • Staff gathering outcome data were blind as to treatment condition.
  • Study Limitation:  This was a small but very well-designed RCT, whose results are reinforced by an RCT of a similar intervention, the Perry Preschool ProjectAlthough we believe these results are extremely important, we caution that these interventions have not yet been demonstrated effective when replicated on a large scale in typical classroom or community settings.


Frances A. Campbell et. al., “Early Childhood Education: Young Adult Outcomes From the Abecedarian Project,” Applied Developmental Science, 2002, vol. 6, no. 1, pp. 42-57.

Leonard N. Masse and W. Steven Barnett,   A Benefit-Cost Analysis of the Abecedarian Early Childhood Intervention,   New Brunswick, N.J.: National Institute for Early Education Research, 2002.

Frances A. Campbell et. al., “The Development of Cognitive and Academic Abilities: Growth Curves From an Early Childhood Educational Experiment,” Developmental Psychology, 2001, vol. 37, no. 2, pp. 231-242.

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