The High/Scope
Perry Preschool Study
Through Age 40
Summary, Conclusions, andFrequently Asked Questions

By Lawrence J. Schweinhart, Ph.D.
President, High/Scope Educational Research Foundation

1

T

he design and findings of the High/Scope
Perry Preschool study and its conclusions
are summarized here, along with answers tofrequently asked questions, thereby taking
advantage of the rich discussion that has surrounded the study over 4 decades. Complete
information is available in the study’s latest
report, Lifetime Effects: The High/Scope Perry
Preschool Study Through Age 40.1

Summary
The High/Scope Perry Preschool study is ascientific experiment that has identified boththe short- and long-term effects of a highquality preschool education program for young
children living in poverty. From 1962 through1967, David Weikart and his colleagues in the
Ypsilanti, Michigan, school district operated
the High/Scope Perry Preschool Program foryoung children to help them avoid school
failure and related problems. They identified asample of 123 low-income African-American
children who were assessed to be at high riskof school failure and randomly assigned 58
of them to a program group that received ahigh-quality preschool program at ages 3 and
4 and 65 to another group that received nopreschool program. Because of the random
assignment strategy, children’s preschool experience remains the best explanation for
subsequent group differences in their performance over the years. Project staff collected
data annually on both groups from ages 3
through 11 and again at ages 14, 15, 19, 27,
and 40, with a missing data rate of only 6%
across all measures. After each period of datacollection, staff analyzed the information andwrote a comprehensive official report.
The study has produced eight monographs over the years. The findings of program effects through age 40 span the domainsof education, economic performance, crime
prevention, family relationships, and health.
Key findings for education, economic performance, and crime prevention are summarized
in Figure 1.

Education
The program group significantly outperformed
the no-program group on highest level ofschooling completed (65% vs. 45% graduating from regular high school). Specifically,a much larger percentage of program than noprogram females graduated from regular highschool (84% vs. 32%). This difference wasrelated to earlier differences between programand no-program females in the rates of treatment for mental impairment (8% vs. 36%)
and grade repetition (21% vs. 41%). The program group also significantly outperformed
the no-program group on various intellectualand language tests from their preschool years
up to age 7; on school achievement tests atages 9, 10, and 14; and on literacy tests at ages
19 and 27. At ages 15 and 19, the program
group had significantly better attitudes toward school than the no-program group, andprogram-group parents had better attitudes
toward their 15-year-old children’s schoolingthan did no-program-group parents.

Economic Performance
Significantly more of the program group than
the no-program group were employed at age
40 (76% vs. 62%), which continues the trend
from age 27 (69% vs. 56%). At age 40, moreprogram-group males than no-program groupmales were employed (70% vs. 50%), although
at age 27 more program-group females thanno-program-group females were employed(80% vs. 55%). The program group also hadeighth monograph of the Perry Preschool study, Lifetime Effects: The High/Scope Perry
Preschool Study Through Age 40 by L. J. Schweinhart et al. (2005), is available from High/Scope
Press, 600 N. River St., Ypsilanti, MI 48198. Contact High/Scope at 1-800-40-PRESS or online atwww.highscope.org. E-mail Larry Schweinhart at lschweinhart@highscope.org.

1 The

2

Figure 1
Major Findings: High/Scope Perry Preschool Study at 40
Program group0%

No-program group

20%

40%
36%

Arrested 5+ times by 40
Earned $20K+ at 40

65%

49%

15%

Homework at 15

significantly higher median annual earnings
than the no-program group at ages 27 and 40($12,000 vs. $10,000 at age 27 and $20,800 vs.
$15,300 at age 40) and higher median monthly
incomes at both ages ($1,020 vs. $700 at age 27
and $1,856 vs. $1,308 at age 40). There was aconsistent tendency for a smaller percentageof the program group than the no-program
group to receive regular income from family
or friends, which was statistically significant
at age 27 (2% vs. 16%).
Rather than paying rent, receiving a subsidy, living with others, or being incarcerated,
the program group had significantly morestable dwelling arrangements at ages 27 and40—that is, more of them owned their own
homes (27% vs. 5% at age 27, 37% vs. 28% at
age 40). At age 40, program males paid significantly more per month for their dwelling than
did no-program males. Significantly moreof the program group than the no-program
group owned a car at age 40 (82% vs. 60%),
especially males (80% vs. 50%), as they had
at age 27 (73% vs. 59%). Indeed, at age 27,
a significantly larger proportion of the program group than the no-program group had a

100%

60%

45%

IQ 90+ at 5

80%

55%

40%

Graduated regular high school
Basic achievement at 14

60%

38%
28%

61%
67%

second car (30% vs. 13%), especially males(36% vs. 15%). At age 40, significantly moreof the program group than the no-program
group had savings accounts (76% vs. 50%),
especially males (73% vs. 36%).
While the evidence of less use of social
services by the program group than by the noprogram group is strikingly consistent acrossvarious indicators of social services usage,
the evidence of a significant group differencein use of social services on individual indicators is equivocal. By age 40, fewer membersof the program group than the no-program
group reported receiving social services atsome time in their lives (71% vs. 86%), but
this difference was not significant. At age 27,
significantly fewer of the program group than
the no-program group reported receiving social services at some time in the previous 10
years (59% vs. 80%). Among the individual
categories of social services, the only significant differences between the program groupand the no-program group involved family
counseling at ages 34 to 40 (13% vs. 24%)
and General Assistance from ages 23 to 27(10% vs. 23%).

3

Crime Prevention
The study presents strong evidence that the
Perry Preschool program played a significant
role in reducing overall arrests and arrests forviolent crimes as well as property and drug
crimes and subsequent prison or jail sentences
over study participants’ lifetimes up to age
40. The program group had significantly fewer
lifetime arrests than the no-program group(36% vs. 55% arrested 5 or more times) andsignificantly fewer arrests for violent crimes(32% vs. 48% ever arrested), property crimes(36% vs. 58% ever arrested), and drug crimes(14% vs. 34% ever arrested). Significant groupdifferences in various types of crime occurredat various times of life—crimes other thanviolent, property, or drug crimes in adolescence (3% vs. 11%); total arrests (7% vs. 29%
with 5 or more arrests) and drug crimes(9% vs. 25%) in early adulthood; and violent
crimes (14% vs. 31%) and property crimes(15% vs. 32%) in midlife. Consider also thatby age 40, compared to the no-program group,
the program group had significantly fewer arrests for property felonies (19% vs. 32% everarrested), drug felonies (7% vs. 28%), violent
misdemeanors (19% vs. 37%), and property
misdemeanors (24% vs. 41%); significantly
fewer arrests for property felonies by age 27(14% vs. 26%); and significantly fewer arrestsfrom ages 28 to 40 for violent felonies (2% vs.
12%), drug felonies (3% vs. 15%), and property misdemeanors (10% vs. 28%). By age 40,compared to the no-program group, the program group had participated in significantly
fewer of 3 of the 78 types of crimes cited atarrest—dangerous drugs (3% vs. 20%), assault
and/or battery (19% vs. 37%), and larceny under $100 (9% vs. 22%). These types of crimes
had significant group differences by age 27;
assault and/or battery also had a significant
group difference at age 28 to 40. Moreover, theprogram group was sentenced to significantly
fewer months in prison or jail by age 40 (28%vs. 52% ever sentenced), specifically fromages 28 to 40 (19% vs. 43%). Also, from ages
28 to 40, the program group was sentenced
to significantly fewer months in prison for
felonies (7% vs. 25%) and had served significantly fewer months in prison overall (9% vs.
21% ever served).

Health, Family, and Children
More program than no-program males raised
their own children (57% vs. 30%) and hadsecond marriages (29% vs. 8%). The twooldest children raised by program-groupmembers did not differ significantly fromthe two oldest children raised by no-program
group members in education, employment,arrests, or welfare status. At age 40, more of
the program group than the no-program groupsaid they were getting along very well with
their families (75% vs. 64%). Fewer program
than no-program males reported using sedatives, sleeping pills, or tranquilizers (17% vs.
43%), marijuana or hashish (48% vs. 71%), or
heroin (0% vs. 9%).

Cost-Benefit Analysis
In constant 2000 dollars discounted at 3%,
the economic return to society of the Perry
Preschool program was $244,812 per participant on an investment of $15,166 perparticipant—$16.14 per dollar invested. Of
that return, $195,621 went to the generalpublic—$12.90 per dollar invested (as compared to $7.16 in the age-27 benefit-cost
analysis), and $49,190 went to each participant—$3.24 per dollar invested. Of the
public return (see Figure 2), 88% ($171,473)
came from crime savings, 4% ($7,303) camefrom education savings, 7% ($14,078) camefrom increased taxes due to higher earnings,
and 1% ($2,768) came from welfare savings.
Preschool program participants earned 14%

4more per person than they would haveotherwise—$156,490 more over their lifetimes
in undiscounted 2000 dollars. Male program
participants cost the public 41% less in crime
costs per person—$732,894 less in undiscounted 2000 dollars over their lifetimes.
Interestingly, 93% of the public return
was due to the performance of males and only
7% to females. This difference is due to thefact that compared to females, males committed substantially more crimes, but program
males committed substantially fewer crimes
than no-program males. This finding stands instark contrast to the earlier finding that 84%
of the program females, but only 32% of the
no-program females, graduated from regularhigh school. Because education is itself aninvestment, it is not surprising that education
cost more for program females, but it is disconcerting that the greater educational attainment of program than no-program females
did not have a larger impact on their earn-ings, as compared to males for whom programand no-program high school graduation rates
were not significantly different. The return tosociety on program investment due to earnings was $70,615 for females as compared to$58,436 for males, only 21% more. We cansurmise that program females did not earnmore because wage growth for low-skilledjobs has been very low in recent decades; notall females participate in the labor market;
and we omitted the benefits of education on
household production and family behaviors.
The cost-benefit analysis is reasonably
conservative in two respects. One is the omission of benefits that are hard to monetize,such as family, health, and wealth benefits.
The other is the conservative assumptions
about the earnings profiles and the unit costsof crimes; where multiple data sources wereavailable, we typically chose the source thatyielded smaller differences between programand no-program groups.

Figure 2
High/Scope Perry Preschool Program Public Costs and Benefits
Education savings

Taxes on earnings

Welfare savings

Crime savings

Benefits$14,078

Total Public Benefit$195,621(Constant 2,000 dollars, 3% discount rate)$200,000$180,000$160,000$140,000$120,000$80,000$60,000$12.90 return per dollar invested.

$40,000$20,000$15,166$0

Costs$171,473$100,000$7,303$2,768

5

Path Model

hood and their school success, economic performance, and reduced commission of crimein adulthood. This study confirms that thesefindings extend not only to young adults,
but also to adults in midlife. It confirms thatthe long-term effects are lifetime effects. The
Perry Preschool study indicates that the return to the public on its initial investment
in such programs is not only substantial but
larger than previously estimated.
The study draws these conclusions
about a 2-year preschool education programfor 3- and 4-year-olds living in low-income
families. Teachers had bachelor’s degrees andcertification in education, and each served
5–6 children. They used the High/Scope educational model in daily 21/2-hour classes andvisited families weekly. In this model, teachers arranged the classroom and daily schedule
to support children’s self-initiated learning
activities, provided both small-group andlarge-group activities, and helped children

A path model of the study (see Figure 3)
suggests how preschool experience affects
participants’ success at age 40. Beginningwith preschool experience and children’s
preprogram intellectual performance, themodel traces cause-effect paths to children’s
postprogram intellectual performance, thento their school achievement and commitment to schooling, then to their educational
attainment, then to their adult earnings andlifetime arrests.

Conclusions
The major conclusion of this midlife phaseof the Perry Preschool research study is thathigh-quality preschool programs for young
children living in poverty contribute to theirintellectual and social development in child-

Figure 3
A Model of the Paths from Preschool Experience to Success at 40

Preschool
Experience

Commitment
at 15
.477

.491

.241

Earnings
at 40
.356

Preprogram IQ

.418

.190

Educational
attainment
by 40

Postprogram IQ

.400

.436

.450

.330

.288

–.265

Achievement
at 14

Arrests
by 40

.203

.070

Note. Path coefficients are standardized regression weights, all statistically significant at p < .01; coefficients ineach box are squared multiple correlations.

6

engage in key experiences in child development. Teachers studied and received regulartraining and support in their use of thiseducational model.
The most basic implication of this study
is that all young children living in low-income
families should have access to preschool
programs that have features that are reasonably similar to those of the High/Scope Perry
Preschool program. Findings from this longterm study and others reviewed in this report
have motivated policymakers to invest more inpreschool programs. But because policymakers
practice the art of political compromise, these
programs have seldom met the standard of reasonable similarity identified here. Recognizing
this problem, more recent efforts, such as the
Abbott court decision in New Jersey and therecent ballot initiative in Florida, have sought
to require key program standards from the be-ginning of a program. These are hopeful signs
and models for the future.
The High/Scope Perry Preschool study
serves as a symbol of what government programs can achieve. The High/Scope Perry
Preschool study also offers a challenge, a kindof policy gauntlet, for decision makers at local,
state, and national levels. It demonstrates what
can be done, and the challenge is to do it. The
High/Scope Perry Preschool, the Abecedarian,and the Chicago programs described in thelatest Perry Preschool report all have significant benefits. Though they illuminate different aspects of the question of lasting effects ofpreschool education, they all reflect the samechallenge of providing high-quality preschool
programs that include low-income children sothat these children get a fair chance to achieve
their potential and contribute meaningfully totheir families and to society.

7

Q&A

B

ecause the long-term High/Scope Perry
Preschool study is well known and respected and stands at the fulcrum of decisions
about public investment in early childhood
programs, it has attracted many questions over
the years that deserve thoughtful answers.
Many of the questions and answers that follow involve the study’s internal and external
validity. Its internal validity is the extent towhich its two groups are the result of simple
random assignment and thus accurately reflect the impact of a good preschool education
experience against the impact of no preschool
education experience. Its external validity is
the extent to which its study participants andtreatment resemble the children and programs
to which it is generalized.

Don’t the departures from random
assignment challenge the internal
validity of the findings?
The internal validity of the High/Scope Perry
Preschool study is very strong because its
design is based on random assignment ofchildren to program and no-program groups.
For this very reason, its departures from strict
random assignment have received intense
scrutiny. These departures and their effects on
major outcomes are examined at length in theage 40 report, Lifetime Effects (Schweinhart
et al., 2005). First, the outcome analyses inthis monograph are adjusted for seven background covariates: five that had statisticallysignificant relationships with preschool experience and one or more of the key outcome
variables; one (mother’s employment) that
had a statistically significant relationshipwith preschool experience due to the randomassignment departure of assigning some children of employed mothers to the no-program

group; and another variable (father at home)that had a nearly statistically significant relationship with monthly earnings at age 40
as well as general policy relevance. Second,
because younger siblings were assigned tothe same group as their older sibling, we analyzed major outcomes with subsamples that
included only one sibling per family. Third,
because the sample consisted of five classesof children, we analyzed major outcomes using classes as covariates. The findings for the
major outcomes were the same regardless ofwhich of these analyses were used.

Isn’t the sample size too small togenerate scientific confidence inthe findings?
Statistical significance testing takes sample
size into account. To achieve statistical significance, group differences must become larger
in magnitude as sample sizes become smaller.
Indeed, a problem with very large samples isthat educationally trivial group differences canachieve statistical significance. If the High/
Scope Perry Preschool study sample were truly
too small, none of its findings would haveachieved statistical significance, and it would
never have become influential.

How can the study be generalized
to other programs?
Because few programs are evaluated by longitudinal studies involving random assignmentof study participants, it is desirable to be able
to generalize the results of such studies as
broadly as possible. The external validity
or generalizability of the study findings extends to those programs that are reasonably

8similar to the High/Scope Perry Preschool
program. A reasonably similar program is apreschool education program run by teachers with bachelor’s degrees and certificationin education, each serving up to 8 children
living in low-income families. The programruns 2 school years for children who are 3
and 4 years of age with daily classes of 21/2
hours or more, uses the High/Scope model ora similar participatory education approach,and has teachers visiting families at least
every two weeks or scheduling regular parent
events. Each term in this treatment definitionis examined further below.
• A preschool education program—a careand education program that contributes
to young children’s development.
• Run by teachers with bachelor’s degrees
and certification in education—The
teachers in the Perry Preschool study
were certified to teach in elementary,
early childhood, and special education;of all their education, the early childhood training was most relevant to theirclassroom practices.
• Each serving up to 8 children—The Perry
Preschool program had 4 teachers for 20
to 25 children, typical for special education classes (Kakalik, Furry, Thomas, &Carney, 1981). The equally successfulclassrooms in the subsequent High/Scope
Preschool Curriculum Comparison study(Schweinhart & Weikart, 1997a, 1997b)
had 2 teachers for 16 children, a ratio of
1 to 8. In general practice, High/Scopepreschool classrooms appear to run successfully with 2 adults and up to 20 children (Epstein, 1993).
• Children living in low-income families—
Children were selected for the study because their parents had low educational
attainment (high school graduation orless), low occupational status (unemployed or unskilled), and their homes

had fewer than 3 rooms per person. Thesefamilies were of lower socioeconomic status than most U.S. residents at that time.
The study does not suggest a sharp cutoff
point for program eligibility.
• Offering 2 school years at 3 and 4 yearsof age—The study presents no evidence
that the program would have had similareffects if it had served children at earlier(infancy–3 years) or later ages (elementary school years). Evidence shows children should attend a similar program for
2 school years (October through May for
the Perry Preschool group); one year isenough only if one accepts a generalization from the 13 program-group membersin the initial class, who attended the program for 1 school year and experienced
the same effects as did the 45 programgroup members in the other classes, who
attended the program for 2 school years.
This study, by itself, offers only weak evidence to support the limitation of manystate preschool programs to only serving
4-year-old children. The better argument
for this policy is the inequity inherent inserving some children for 2 school years
when, as a result, other eligible children
are not served at all, because the 3-yearolds served have taken the places ofadditional 4-year-olds.
• With daily classes of 21/2 hours or more—
The program runs at least 21/2 hours a day
5 days a week. A few minutes less should
not matter, nor should hours more: Evena full, 9-hour-a-day program, if it meets
all the other standards of quality, should
produce similar if not greater effects.
• Using the High/Scope educational modelor a similar participatory education
approach—The High/Scope educationalmodel was developed and used in the
program (Weikart, Deloria, Lawser, &Wiegerink, 1970; Hohmann, Banet, &Weikart, 1979; Hohmann & Weikart,

9

1995, 2002). In this model, the classroom
is arranged and the day is scheduled tosupport children’s self-initiated learning
activities along with small-group andlarge-group activities. Teachers help children as they plan, carry out, and review
their own activities. Teachers plan ways
to engage children in numerous key experiences in child development covering
the areas of personal initiative, social
relations, creative representation, movement and music, logic and mathematics,
and language and literacy. Teachers study
and receive regular training in the educational model and receive support inits use from a supervisor who knows themodel and assists in its implementation.
• With teachers visiting families at least
every 2 weeks—The program included
weekly home visits, which might be reduced to every 2 weeks, or changed to an
equivalent form of substantial outreachto parents, such as parent group meetings in which staff acknowledge andsupport parents as partners in the education of their children and model activelearning principles for them. The key is
not to require meetings, but rather to ensure that the basic message and lessonsof a strong partnership with parents areclearly and repeatedly communicated.
Sometimes, issues including the safetyof home visitors in the community callfor creative solutions to this challenge.
The study provides scientific evidence
that its findings apply to reasonably similar
programs. Program similarities, however, aredefined somewhat more liberally than theactual program characteristics to allow fornecessary and reasonable variations—serving
up to 8 children rather than 5 or 6, serving
children living in low-income families rather
than only families living in poverty, home

visits every 2 weeks rather than every week(or regular parent meetings and events). These
characteristics are structural, that is to say,they are relatively easy to name, count, legislate, regulate, and monitor. One of them,use of the High/Scope educational model, is
structural in its simplest meaning, but encompasses process characteristics as well, that is,what actually happens in the classroom, suchas the nature of teacher-child interaction.
Programs with similar features, regardless ofmodel used, can expect similar results. In curriculum provision, it’s not what you say you
do but what you actually do that counts.

Were the findings due to curriculum
or other aspects of the program?
The High/Scope Preschool Curriculum
Comparison study (Schweinhart & Weikart,
1997a, 1997b), which immediately followed
the High/Scope Perry Preschool study, suggests that the curriculum had a lot to do withthe findings. The comparison study foundthat young people born in poverty experienced fewer emotional problems and felonyarrests if they attended a preschool programthat used the High/Scope model or a traditional Nursery School model rather than a
Direct Instruction model.
Since 1967, the study has followed thelives of 68 young people born in poverty whowere randomly assigned at ages 3 and 4 to oneof three groups, each experiencing a different
curriculum model:• In the Direct Instruction model, teachers
followed a script to directly teach children
academic skills, rewarding them for correct answers to the teacher’s questions.2• In the High/Scope model, teachers set
up the classroom and the daily routine
so children could plan, do, and review

2 This 1960s model has undergone subsequent development and current versions differ from theone in this study.

10

their own activities and engage in active
learning key experiences in child development individually, in small groups,
and in whole-class groups.
• In the traditional Nursery School model,teachers responded to children’s selfinitiated play in a loosely structured,socially supportive setting.
Program staff implemented the curriculum models independently and to high standards, in 21/2-hour classes held 5 days a week,
and conducted 11/2-hour home visits every 2
weeks, when children were 3 and 4 years old.
Except for the curriculum model, all aspectsof the programs were nearly identical. The
findings presented here are corrected for differences in the gender makeup of the groups.
By age 23, the High/Scope and Nursery
School groups had 10 significant advantages
over the Direct Instruction group, and theHigh/Scope and Nursery School groups did
not differ significantly from each other on any
outcome variable (Schweinhart & Weikart,
1997b). The High/Scope and Nursery Schoolgroups both had two significant advantages
over the Direct Instruction group at age 23:compared to 38% of the Direct Instructiongroup.
• At age 15, 23% of the High/Scope groupreported that they had engaged in 10 ormore acts of misconduct, as compared to
56% of the Direct Instruction group.
• Fewer of the High/Scope group (36%)
said that various kinds of people gavethem a hard time, as compared to 69%
of the Direct Instruction group.
• With regard to marriage, 31% of theHigh/Scope group had married and were
living with their spouses, as compared tonone of the Direct Instruction group.
• Of the High/Scope group, 70% planned
to graduate from college, as compared to
36% of the Direct Instruction group.
The Nursery School group had two additional significant advantages over the Direct
Instruction group:• Only 9% of the Nursery School group
had been arrested for a felony at ages
22–23, as compared to 34% of the Direct
Instruction group.

• Only 6% of either group needed treatment
for emotional impairment or disturbanceduring their schooling, as compared to
47% of the Direct Instruction group.

• None of the Nursery School group had
ever been suspended from work, as compared to 27% of the Direct Instructiongroup.

• More of the High/Scope group (43%) andthe Nursery School group (44%) had done
volunteer work, as compared to only 11%of the Direct Instruction group.

Through age 10, the main finding of the
Preschool Curriculum Comparison study wasthat the overall average IQ of the three groupsrose 27 points—from a borderline impairment
level of 78 to a normal level of 105 after 1 yearof their preschool program—and subsequently
settled in at an average of 95, still at thenormal level. The only curriculum group difference through age 10 was measured as thepreschool programs ended: the average IQ of
the Direct Instruction group was significantly
higher than the average IQ of the Nursery
School group (103 vs. 93). Throughout theirschool years, curriculum groups did not

The High/Scope group had six additional significant advantages over the Direct
Instruction group:• Only 10% had ever been arrested for afelony, as compared to 39% of the Direct
Instruction group.
• None of the High/Scope group had everbeen arrested for a property crime, as11differ significantly in school achievement, nor
did their high school graduation rates differ
significantly. The conclusion at that time wasthat well-implemented preschool curriculum
models, regardless of their theoretical orientation, had similar effects on children’s intellectual and academic performance. However,time has proved otherwise. Tightly scripted
teacher-directed instruction, touted by someas the surest path to school readiness, seems
to purchase a temporary improvement inacademic performance at the cost of a missed
opportunity for long-term improvement insocial behavior.

Does the High/Scope Perry Preschool
study apply to Head Start and statepreschool programs?
Because of the demand for knowledge ofthe lasting benefits of preschool education
programs, there has been a tendency togeneralize the High/Scope Perry Preschool
study’s findings beyond reasonably similar
programs. Several of these generalizations
deserve discussion here.
The most common generalizations of theHigh/Scope Perry Preschool study findings
relate to the national Head Start program.
Indeed, news reports have often impreciselyreferred to the Perry Preschool Program study
as a Head Start program (see discussion by
Woodhead, 1988). News reporters would argue
that this conflation of terms is a useful convenience to simplify the story in that both the
Perry Preschool program and Head Start serve
young children living in poverty and began
in the U.S. in the 1960s. Nonetheless, Head
Start, as nationally defined by its Program
Performance Standards (U. S. Administration
for Children and Families, 2001), clearly does
not meet the standard of reasonable similarity
with the Perry Preschool program for generalization purposes:• Most Head Start teachers do not havea bachelor’s degree. In 2000, only 28%
of Head Start teachers had a bachelor’s
degree, while 19% had an associate’s
degree, 32% had some college experience but no degree, and 74% had a Child
Development Associate credential orstate-awarded preschool certificate (Zillet al., 2003). Teacher salaries in Head
Start average $21,000—about half of theaverage of $43,000 for public school
teacher salaries (National Institute for
Early Education Research, 2003)—while
teacher salaries in the High/Scope Perry
Preschool program were at public school
teacher salary levels at the time of thestudy, with a 10% bonus for participation in a special program.
• Head Start serves most but not all participating children for 2 or more program
years. In FY 2003, for example, 34% of
Head Start children were 3 years old, 53%
were 4 years old, 5% were 5 or older, and
8% were under 3 (U. S. Administration
for Children and Families, 2004). In FY
2002, 36% of Head Start children were 3
years old, and it is reasonable to assume
that these children continued in Head
Start as 4-year-olds in FY 2003, so thatmost of the 4-year-olds in Head Start in
FY 2003 (36% among the 53%) had beenin the program the previous year. We cantherefore surmise that in FY 2003 only
17% of Head Start 4-year-olds attended
the program for only one year.
• Only 20% of Head Start programs report using the High/Scope educational model, while 39% report using theCreative Curriculum model, and 41%
report using some other curriculum approach (Zill et al., 2003). The Creative
Curriculum model has goals similar to
the High/Scope model, but emphasizes
different practices to attain these goals(Dodge, Colker, & Heroman, 2002).

12• Head Start Program Performance Standards
require only 2 home visits a year.
The Head Start Family and Child
Experiences Survey (FACES) found that children gained 4 points in standard scores on the
Peabody Picture Vocabulary Test during their
Head Start year (Zill et al., 2003). Children in
the High/Scope Perry Preschool study gained
8 points in their first year and a total of 14
points in 2 years. In other words, on average
Head Start programs are achieving some success, but could be doing more to help children reach their potential.
Forty states have now invested in statepreschool programs for young children living
in poverty or otherwise at special risk of school
failure (Barnett, Robin, Hustedt, & Schulman,
2003; National Prekindergarten Center, 2003).
As these programs have developed, especiallyin the past 2 decades, policymakers have paid
attention to program quality, thereby acknowledging the argument from the High/Scope
Perry Preschool study and similar studies that
only high-quality preschool programs for poor
children are known to have long-term benefits
for participants and a strong return on public
investment. However, politics is the art ofcompromise, and the high quality of the High/
Scope Perry Preschool program (as definedearlier) is seldom if ever achieved in state preschool programs (Gilliam & Zigler, 2004).
The simple scientific conclusion is thatthe findings of the High/Scope Perry Preschool
study do not apply to typical Head Start orstate preschool programs, but may apply to
exemplary ones and could apply to typicalones if policymakers and administrators choseto implement the standards of high quality
described here. It is important to get this point
just right, neither overstating nor understating
the Perry Preschool program study’s generalizability. While the findings do not apply totypical Head Start programs as they exist today,
it is not because the program studied was an
unattainable ideal run by super-educators, thelikes of which will never be seen again. To borrow a phrase from Lisbeth Schorr, the programs
and findings presented in the Perry Preschool
study monographs are completely and realistically “within our reach” (Schorr, 1989, p. i.).

Does the study apply to child careprograms?
Several studies of U.S. child care centers haveconcluded that their quality is unacceptably
low (Cost, Quality, & Child Outcomes Study
Team, 1995; Whitebook, Phillips, & Howes,
1993). In terms of the quality criteria listed
here, child care programs have certain seemingly insurmountable financial problems.
Unlike Head Start and state preschool programs, which are fully paid for by the government, an estimated 60% of child care costs areborne by the participating families (Stoney &Greenberg, 1996). While child care programs
can certainly aspire to be genuine preschool
education programs and maintain a ratio of
no more than 8 children per teacher, the needfor child care includes, but also extends wellbeyond, 3- and 4-year-old children. By definition, these programs could serve all children
whose parents are employed or in school outside the home, a definition that includes but
is not limited to low-income children.
For the most part, the average pay forchild care teachers is less than half that of
public school teachers ($43,000). The average annual wage for child care workers in2002 was $23,820 in local-government programs, $18,279 in state and federal programs,$15,155 in private programs, and $11,507 forself-employed child care workers (National
Child Care Information Center, 2004a). It
should come as no surprise that only one
state, Rhode Island, requires child care teachers to have bachelor’s degrees, and only 15
states have any educational requirements at
all for child care teachers (National Child
Care Information Center, 2004b).

13

The High/Scope educational model
widely influences teaching practices in childcare programs; but the meager funds available
for training in child care programs mean thatfew providers actually receive much training
in the High/Scope model. Daily classes certainly do run more than 21/2 hours, and there
is no reason to think that their additional
duration per se prevents program staff fromdelivering as much or more quality education
as briefer programs. Teachers do not provide
regular home visits to families, but that would
not be the correct standard to use in these cases.
Rather, the child care programs’ challenge
is to develop teacher-parent relationships of
mutual respect and understanding that areof the same quality as those that result frombiweekly home visits or regularly scheduledparent meetings.

Does the study apply to openenrollment preschool programs?
The relatively new open enrollment preschool
programs have also been linked to the High/
Scope Perry Preschool study findings. These
programs are sometimes called universal andother than age and residence requirements,
have no demographic restrictions (such as
poverty) on program enrollment. The findingsof the High/Scope Perry Preschool study andsimilar studies would apply only to children
served by these programs who are reasonably
similar to children living in poverty or otherwise at risk of school failure.
It is important to keep in mind, however, that poverty is not an inherent traitof children but is rather a socioeconomic
extreme of settings in which they live. A
good preschool program offers a productive
early childhood educational environment,
while early childhood poverty by and large
offers an unproductive early childhood educational environment. So the longitudinalpreschool studies provide evidence that thedegree of educational productivity in earlychildhood settings has a large influence on
young children’s subsequent lives. All young
children spend their time in settings that varyin their educational productivity, so the findings apply in this way to all children. But
if it is a setting’s educational productivity
that matters, early childhood programs are
not inherently more educationally productive than children’s homes, nor are children’s
homes inherently more productive than earlychildhood programs. Young children fromeducationally productive homes who attend
less educationally productive early childhood programs would suffer negative effects
on their development. The survey of existingpreschool settings in the previous paragraphs
gives reason to be seriously concerned about
this reverse application of the findings of thelongitudinal preschool program studies.

Does the study apply to early childhood programs in other countries?
As the characteristics of a country’s children
and programs diverge from the characteristicsof the Perry Preschool study’s children andprograms, applications become less certain.
Generalization of the study to other industrialized countries, such as Great Britain, seems
probable, but generalization of the study toless industrialized countries requires greater
caution. The challenge of such applications
becomes clear as one considers the practical ranges of outcome variables in various
countries. Improving the high school graduation rate, for example, is a reasonable goalin industrialized countries, but not in someless industrialized countries. One might reasonably argue, however, that a high-qualitypreschool program would improve children’s
educational performance in less industrialized countries, but that this effect would be
expressed in ways other than an improved
high school graduation rate. For example, the14Turkish Early Enrichment Project (Kagitcibasi,
Sunar, & Bekman, 2001) found evidence oflong-term program effects on children’s educational success and social adjustment in avery different culture. Cost-benefit analysis
is particularly sensitive to such differences
between countries.

Did the Perry Preschool program
occur too long ago to apply to current
programs?
The Perry Preschool Project operated from1962 through 1967. The rapid pace of technological change in modern society—including
the advent of widespread use of computers, worldwide electronic communication,and increased transportation, among otheradvances—is unprecedented in history. But
there is no compelling reason to assume that
this rapid pace of technological change would
alter basic principles of human behavior andeducation. Throughout most of the historyof the world, few would have regarded halfa century or even a century as a sufficientamount of time to permit profound changes
in traditions, let alone profound changes inhuman nature that would affect how children
respond to an educational program. Indeed,
the education and social sciences in general are quests for timeless principles, not forprinciples that must be rediscovered once or
twice a decade. The argument that the finding of such studies have limited applicability to the present because of rapid change
is quite similar to a belief that because eachhuman experience is unique, scientific generalization is impossible. A current manifestation of this belief is the postmodernism
movement (Dahlberg, Moss, & Pence, 1999).
Postmodernism is essentially a nonscientificmovement, even antiscientific. In contrast,
the scientific approach adopted in the High/
Scope Perry Preschool study is the logicalapplication of the principle that similar expe-

riences have similar effects on human development—what might be called the principleof external validity or generalizability.

Does the evidence of the effectivenessof the High/Scope educational model
come only from programs run
decades ago?
No. The Head Start FACES study (Zill et al.,2003) is a nationally representative study of
2,800 children who entered Head Start in fall
2000. It found that 4-year-olds in Head Start
classes that used High/Scope improved fromfall to spring in letter and word identification
skills and cooperative classroom behavior
and decreased their behavior problems:• On a scale of letter and word recognition, children in High/Scope classes registered a highly significant gain (p < .01)
of 12.6 scale points, significantly more(p < .05) than children in classes using
Creative Curriculum or other curricula.
• On teacher ratings of cooperative classroom behavior, children in High/Scopeclasses experienced a highly significant
gain (p < .01) of half a standard deviation,
significantly more (p < .05) than children
in classes using Creative Curriculum orother curricula.
• On teacher ratings of total behavior problems, particularly problems involving
hyperactive behavior, children in High/
Scope classes dropped significantly(p < .05) during the year, significantly
more (p < .05) than did children in classes using Creative Curriculum or othercurricula.
Of the 91% of Head Start teachers who
used one or more curriculum models, 39%
used Creative Curriculum, 20% used High/
Scope, and 41% used some other curriculum,15

such as High Reach, Scholastic, or Los Cantos
Los Ni§os. The quality of Creative Curriculumand High/Scope classes was significantly higher than the quality of classes that used othercurricula, particularly with respect to language.
On the 7-point Early Childhood Environment
Rating Scale (Harms, Clifford, & Cryer, 1998),
with 5 identified as good, High/Scope classes
averaged 5.04, Creative Curriculum classes averaged 5.02, and classes using other curricula
averaged 4.55. On its language items, averagescores were slightly higher, but the differenceswere about the same. On a quality composite,
the average scores for High/Scope and Creative
Curriculum were nearly half a standard deviation higher than the average scores for othercurricula—clearly an educationally meaningful difference.
The High/Scope Training for Quality
study (Epstein, 1993) also offers evidence
for the effectiveness of the High/Scope preschool model as practiced throughout the
U.S. Half of High/Scope-certified trainers inthe study were in Head Start, 27% were in
public schools, and 20% were in private childcare agencies. They had a median 15 years ofearly childhood experience, 88% had completed college, and 85% had teacher-training responsibility—spending an average of 8hours a week training teachers. At the timeof the study, the High/Scope Registry listed
1,075 early childhood leaders in 34 statesand 10 other countries who had successfullycompleted High/Scope’s 7-week trainer certification program in the past decade. The
average trainer had trained 15 teaching teams,
so an estimated 16,125 teaching teams, including 29% of all Head Start staff, had received
High/Scope model training from these trainers. Since trainers regard 45% of these classrooms as examples of the High/Scope model,
they would nominate an estimated 7,256 earlychildhood classrooms throughout the U.S. andaround the world as examples of the High/
Scope model. High/Scope classrooms wererated significantly better than comparison
classrooms in terms of classroom environment, daily routine, adult-child interaction,and overall implementation. The children in
High/Scope programs significantly outperformed the children in comparison programs
in initiative, social relations, music and movement, and overall child development.

Didn’t the High/Scope Perry Preschool
program achieve a level of qualitythat cannot be duplicated in ordinarypreschool programs?
This criticism is rooted in the fact that theHigh/Scope Perry Preschool program paidteachers public school salaries and added a
10% bonus because the program was a special one. There is no reason to think that such
pay would have attracted teachers who were
substantially better than other public school
teachers, and in fact the teachers who worked
in the program were hired locally by ordinary
search and hiring procedures. Nevertheless,current child care (and Head Start) teacher
salaries average only about half as much as average public school teacher salaries (National
Institute for Early Education Research, 2003).
More and more preschool programs, however,are hiring teachers at public school salaries.
It has also been suggested that the quality of
the Perry Preschool program was due, in part,to the charismatic leadership of the program’s
director, David Weikart (Schorr, 1989). While
Weikart’s leadership was certainly essential tothe program’s success, there is every reason tobelieve that any dedicated preschool program
director could exercise similar leadershipwith respect to assuring the quality of the
programs under his or her supervision. Suchleaders insist on program quality and fidelity
to a validated educational model and strive toprovide program staff with all the resourcesand encouragement they need to achievethem, including adequate salaries.

16

Although the program had a strong
effect on children’s intellectual
performance, didn’t it fade out
over time?
It is true that the High/Scope Perry Preschool
program had a statistically significant effect onchildren’s IQs during and up to a year after the
program, but not after that. This pattern has
been found in numerous other studies, suchas those in the Consortium for LongitudinalStudies (1983). The pattern raises two questions: How far does it generalize, and what
does it mean?
For some time, the pattern of children’s
intellectual performance found in this study
was taken to represent all outcomes of thisand similar programs. It was concluded thatthe program had strong effects that faded out
over time. However, all of the subsequentfindings of program effects in this study(effects on school achievement, high school
graduation, adult earnings, and crime prevention) disprove this conclusion. Indeed, so manystudies have now found evidence of long-term
effects of high-quality preschool programs
that the opposite conclusion is practically indisputable: High-quality preschool programsfor young children living in poverty do havelong-term effects.
So what is the meaning of the fadeout of
program effect on children’s intellectual performance? More than anything else, it teaches
us about the nature of multiage intelligencetests. Unlike most achievement tests that are
age-specific, most intelligence tests, like theStanford-Binet (Terman & Merrill, 1960), aredesigned to be used with individuals of awide range of ages, from early childhood toadulthood. Also unlike achievement tests,
intelligence tests were not designed to assess
program effects, and so the way they functionin this role was not, and is not, well under-stood. Multiage intelligence tests actuallyconsist of a series of age-specific test batteries(the Stanford-Binet has 6 items per battery)
designed to function with a specific age level,such as children 4 years old or children 4
years and 6 months of age. The preschoolstudies found effects at the ages during anda year or two after the program, but not subsequently. Children with preschool program
experience got more items right on those agespecific batteries, but did not get more righton age-specific batteries designed for older
children. It seems reasonable to conclude
that, when used to assess preschool program
outcomes, intelligence tests functioned more
like achievement tests than intelligence tests,
and indeed that is precisely the use to which
they were put. Imagine if achievement tests
for grades 4–8 were all combined into one
grand multiage test of achievement. It would
not be at all surprising if a really good grade
4 classroom improved children’s achievement
test scores on this test at grades 4 and 5, but
not at grades 6, 7, and 8. That is precisely
what happened in the temporary effects ofhigh-quality preschool programs on children’s
intellectual performance.
To take this thinking to a theoretical level
regarding children’s intellectual performance,
we might simply say that the preschool studies showed intellectual performance to beenvironmentally sensitive—it went up in
intellectually stimulating preschool settingsand down in less intellectually stimulating
elementary school settings. Or, to put it interms of program and no-program groups, itwent up when the program group’s experience was more intellectually stimulating thanthat of the no-program group and returned tothe same level as that of the no-program groupwhen both found themselves in the sameelementary school settings.

17

Was the preschool program’s effect on
intellectual performance critical to its
success and can this goal be replacedby another goal, such as early literacy
skills and other content?
The causal model presented in the Lifetime
Effects monograph (Schweinhart et al., 2005)
identifies intellectual performance as thegateway from the preschool program to all
subsequent program effects. However, theoriginal hypothesis was that a good preschool
program would increase children’s intellectual performance permanently, not temporarily;
and typically, after early childhood, intellectual performance does not change much
(Terman & Merrill, 1960). Perhaps rather thanidentifying the gateway variable as early childhood intellectual performance, we should callit the preschool intellectual boost.
The High/Scope educational model was
originally called the Cognitively Oriented
Curriculum (Weikart et al., 1970) because it
focused on cognitive, logical processes identified in Piaget’s theory of education (Piaget &Inhelder, 1969)—such as representation, classification, and seriation. Tests of early childhood
intellectual performance demonstrably tap theseprocesses. So the High/Scope preschool classroom provides a preschool intellectual boost as
measured by these tests. It also provides otherexperiences that facilitate these intellectual processes, such as planning and reviewing one’s
activities, exploring what one is curious about,and developing a sense of personal control overthe events of one’s life—what might be called
intellectual performance, broadly defined.
It makes sense to combine or supplement this emphasis on intellectual processes
with a focus on early literacy or mathematics
skills found to predict later achievement, but
it does not make sense to replace the first withthe second. To do so runs the risk of sacrificing the known long-term effects on school
achievement, high school graduation rates,
lifetime earnings, and crime prevention.

Why did the High/Scope Perry
Preschool Program affect males andfemales differently?
Males and females in this study differed
substantially from each other on educational
attainment and lifetime arrests.
Evidence of stronger program effects on
females appears for regular high school graduation rate, repeating a grade, and treatment
for mental impairment. Over 21/2 times as
many program females as no-program females
graduated from regular high school (84% vs.
32%), whereas about the same percentagesof program and no-program males graduatedfrom regular high school (50% vs. 54%). Half
as many program females as no-program females repeated a grade (21% vs. 41%), whileslightly more program males than no-program
males repeated a grade (47% vs. 39%). Less
than one-fourth as many program females as
no-program females (8% vs. 36%) were treated for mental impairment, while only twothirds as many program males as no-program
males were treated for mental impairment(20% vs. 33%).
Evidence indicates that the program effect on criminal arrests was stronger for males
than for females, partly because males had
more arrests: 69% of no-program males, but
only 34% of no-program females, were arrested five or more times. The apparent program
effect in persons with five or more arrests wasa reduction of about one third for males (45%vs. 69%) and for females (24% vs. 34%),
but because the percentages were higher formales, the reduction in number of arrests was
greater. The starkest gender difference was inarrests for drug crimes, for which less thanhalf as many program males as no-program
males were arrested (18% vs. 49%), while thepercentages were about the same for programand no-program females (8% vs. 11%).
A possible explanation for this patternis that teachers and school staff responded
differently to girls and boys whose academic

18

performance improved as a result of receiving the preschool program. As would be expected, educators responded to the preschool
program’s effect on girls’ early academic performance by keeping them in regular classes
rather than by having them repeat a grade orby assigning them to special classes for mental
impairment. Girls who were not tracked into
repeated grades or special classes were more
likely to graduate from regular high school.
On the other hand, boys in the program andno-program groups were retained in grade
and assigned to special classes for mental im-

pairment at about the same rate, despite better
performance on intellectual tests by the group
who had preschool. This may be because
teachers and school staff focused primarily onclassroom misconduct (more common in bothgroups of boys than in the girls) rather than on
objective measures of academic performancesuch as intellectual tests. For this reason, theintellectual gains made in preschool by themale program group may not have translated
as expected to gains in high school graduation rate and in other long-term indicators ofeducational success.

19

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