The Chicago Longitudinal Study

The Chicago Longitudinal Study is a federally-funded investigation of the effects of an early and extensive childhood intervention in central-city Chicago called the Child-Parent Center (CPC) Program. The study began in 1986 to investigate the effects of government-funded kindergarten programs for 1,539 children in the Chicago Public Schools.

The study is in its 20th year of operation. Besides investigating the short- and long-term effects of early childhood intervention, the study traces the scholastic and social development of participating children and the contributions of family and school practices to children's behavior. The CPC program provides educational and family support services to children from preschool to third grade. It is funded by Title I and has operated in the Chicago Public Schools since 1967

High/Scope Perry Preschool Study

This study examines the lives of 123 children born in poverty and at high risk of failing in school.From 1962–1967, at ages 3 and 4, the subjects were randomly divided into a program group that received a high-quality preschool program based on HighScope's participatory learning approach and a comparison group who received no preschool program. In the study's most recent phase, 97% of the study participants still living were interviewed at age 40. Additional data were gathered from the subjects' school, social services, and arrest records.
The study found that adults at age 40 who had the preschool program had higher earnings, were more likely to hold a job, had committed fewer crimes, and were more likely to have graduated from high school than adults who did not have preschool.


​Comparing the preschool group to the no-preschool group, we found the following significant differences through age 27:

  • Incidence of crime. Only 7% of adults who had participated in the Perry Preschool program had been arrested five or more times, compared with 35% of those who had not participated in a preschool program. Of those in the preschool program group, 7% had never been arrested for drug-related offenses, compared to 25% of those in the no-program group.
  • Earnings and economic status. Adults in the program group were four times more likely (29%) to earn $2,000 or more per month than were adults in the no-program group (7%). Almost three times as many (36%) owned their own homes, compared to those in the no-program group (13%). More than two times as many (program 30%, no program 13%) owned a second car. As adults, 59% of those in the program group had received welfare assistance or other social services at some time, compared to 80% of those in the no-program group.
  • Educational attainment. Seventy-one percent of those in the program group graduated from regular or adult high schools or received General Education Development certification, compared with 54% of those in the no-program group. Earlier in the study, the preschool program group had significantly higher average achievement scores at age 14 and literacy scores at age 19.
  • Marriage and single parenthood. Forty percent of women in the program group were married at the time of the age-27 interview, compared to 8% of those in the no-program group; and 57% of women in the program group were single parents, compared to 83% of those in the no-program group.

Head Start Impact Study

Head Start provides comprehensive early child development services to low-income children, their families, and communities. In 1998, Congress determined, as part of Head Start's reauthorization, that the Department of Health and Human Services (DHHS) should conduct a national study to determine the impact of Head Start on the children it serves. In October 2000, DHHS awarded a contract to Westat in collaboration with the Urban Institute, American Institutes for Research, and Decision Information Resources to conduct this study through spring of the children’s first grade year. 

The National Head Start Impact Study has two primary goals. The first is to determine on a national basis how Head Start affects the school readiness of children participating in the program as compared to children not enrolled in Head Start. Does Head Start improve children's cognitive development, general knowledge, approaches to learning, social and emotional development, communication skills, fine and gross motor skills, and physical well-being? In addition, how does Head Start affect the lives of the families of children enrolled in the program?

The second goal of the study is to determine under which conditions Head Start works best and for which children. To meet this goal, the study will examine various factors that could affect the results of the Head Start program. These factors will include differences among children attending Head Start, differences in children's home environments, the different types of Head Start programs available (home or center-based, quality indicators such as staff ratio, curriculum, part- vs. full-day programs, one versus two years exposure), and the availability and quality of other child care and preschool programs in a particular area.


​The National Head Start Impact Study is a longitudinal study that involves approximately 5,000 three and four year old preschool children across 84 nationally representative grantee/delegate agencies in communities where there are more eligible children and families than can be served by the program. The children participating were randomly assigned to either a treatment group (which had access to Head Start services) or a comparison group (which did not have access to Head Start services, but could receive other community resources).

Data collection began in the fall of 2002 and ended in spring 2006, following children through the spring of their first grade year. It includes in-person interviews with parents; in-person child assessments; direct observations of the quality of different early childhood care settings; and teacher ratings of children.


In 2006, DHHS awarded another contract to Westat and its colleagues (Chesapeake Research Associates, Abt Associates, American Institutes for Research, the University of Virginia Center for the Advanced Study of Teaching and Learning, AMSAQ) to follow the Head Start Impact Study children and their families through spring of their third grade year.


Dr. Ballard brought up the following point about the study: 

​The Head Start Impact study was designed to study whether Head Start was effective.  The study found that the impact of Head Start versus the control group was no different by third grade.  However, there were some issues with the study. This link provides information from the National Head Start Association on the study: Head Start Impact Study New and Policy Update


This study is commonly being used to make the case that early childhood has no long term benefits.  However, it is not an appropriate use of the study since 60% of the children in the control group actually attended an early childhood program. In fact, 14% of the four year old control group and 18% of the three year old control group attended other Head Starts that were not involved in the study.  

A recent study compared the 40% of children in the control group who were not in an early childhood program with the Head Start group and found better outcomes for the Head Start children 

The Abecedarian Project

The Abecedarian project was a carefully controlled scientific study of the potential benefits of early childhood education for poor children. Four cohorts of individuals, born between 1972 and 1977, were randomly assigned as infants to either the early educational intervention group or the control group.

  • Children from low-income families received full-time, high-quality educational intervention in a childcare setting from infancy through age 5.
  • Each child had an individualized prescription of educational activities.
  • Educational activities consisted of "games" incorporated into the child's day.
  • Activities focused on social, emotional, and cognitive areas of development but gave particular emphasis to language.
  • Children's progress was monitored over time with follow-up studies conducted at ages 12, 15, and 21.
  • The young adult findings demonstrate that important, long-lasting benefits were associated with the early childhood program.


Major Findings

  • Children who participated in the early intervention program had higher cognitive test scores from the toddler years to age 21.
  • Academic achievement in both reading and math was higher from the primary grades through young adulthood.
  • Intervention children completed more years of education and were more likely to attend a four-year college.
  • Intervention children were older, on average, when their first child was born.
  • The cognitive and academic benefits from this program are stronger than for most other early childhood programs.
  • Enhanced language development appears to have been instrumental in raising cognitive test scores.
  • Mothers whose children participated in the program achieved higher educational and employment status than mothers whose children were not in the program. These results were especially pronounced for teen mothers.