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children who will perform poorly in school, become teenage

parents, commit criminal acts, or depend on welfare.

Although some projects have had meaningful short-term

effects on disadvantaged children's cognitive ability,

grade retention, and special education placement, those

benefits are short-lived.  At the same time, most inter-

ventions have concentrated on disadvantaged children, so

there is no evidence for universal replicability.  In

fact, a large body of evidence shows that preschool can

have a negative impact on middle-income children.

Few studies have examined or demonstrated long-term

effects of intervention on children's development.  Most

attempted studies were of model programs and were impaired

by small sample size, attrition, and selection bias and

were severely limited in statistical power and generaliz-

ability.  The two projects that provide the most valid

estimates of the long-term effects of early intervention on

disadvantaged children--Perry Preschool and Abecedarian--do

not support the claims made by advocates of universal pre-

school.  Finally, even if there were reliable evidence of

lasting, long-term effects of early intervention on disad-

vantaged children, it would still be necessary to show that

those effects could be generalized to a program of state or

national scope.  As the following section details, the gov-

ernment's longest running preschool program for disadvan-

taged children, Head Start, has failed to produce long-term

benefits for participating children.

Head Start

Research on Head Start is relevant to the universal

preschool debate because the program has many characteris-

tics of a large-scale, public preschool program.  Unlike

model programs, which typically have been small in scale

and conducted under ideal circumstances, Head Start is a

large-scale program operating under real-world conditions

and constraints.  And unlike research on model programs,

which usually offers snapshots in place and time, research

on Head Start has been conducted across the country over a

33-year period.  Furthermore, fundamental to the program's

philosophy is the notion that communities should have con-

siderable latitude to develop their own programs.  That

variability is likely to be comparable to the variability

one would find among public preschools within school dis-

tricts and across states.

Ron Haskins, administrative director of the

Abecedarian Project from 1977 to 1980 and now staff direc-

tor of the Human Resources Subcommittee of the House Ways