The Head Start program is, in the words of founder Edward Zigler, "America's most successful education experiment." Zigler is exactly right, if success is measured by good public relations.

Politicians from both major parties are fond of touting Head Start, the popular federal program that provides preschool and health services to poor children. Social activists, educators and journalists love it (for the latter, the smiling faces of preschoolers make for excellent television). Even business leaders who are otherwise frustrated and disgruntled with "business as usual" in education policy support it. President Clinton wants to spend more on it.

What is it about this 30-year old, $2.2 billion program that so many find attractive? Without a doubt, it is the widely-held belief that investing a public dollar now in Head Start will save many more dollars in the future. The program's advocates argue that if we can intervene early enough in poor children's lives, giving them a boost toward becoming good students and well-adjusted teens, then many of them will not grow up to be welfare mothers, deadbeats or criminals.

It's a nice thought, but there's a snag in the sales pitch: There is virtually no evidence that Head Start has any significant impact on children's lives in the long run. Zigler's praise would be much more accurate if he had described the program as "America's most successfully oversold education experiment."

Certainly, Head Start children tend to score better than their peers when they enter first-grade. But after about two years of public school, the disadvantaged who attended Head Start tend to perform at about the same level as those who did not--that is, poorly. Two years is all it takes for the educational "gains" from Head Start to disappear.

A 1985 analysis by the Department of Health and Human Services found that ambitious claims for Head Start's long-term effects were exaggerated. "In the long run," the department's report noted, "cognitive and socio-emotional test scores of former Head Start students do not remain superior to those of disadvantaged children who did not attend Head Start." More recent research confirms that conclusion.

The source of all the hype about Head Start is really the experience of a few atypical, idiosyncratic preschool programs whose specific designs include a great deal of parental involvement, funding, and staff training. The most famous of these is located here in Michigan--at the Perry Preschool in Ypsilanti.

In 1962, Perry selected 123 poor children to take part in an experiment. Half the group was given two years of preschool instruction and services, two and a half hours a day, five days a week. The other half--the experiment's control group--took part in no preschool program. The children were then tracked throughout their academic careers into adulthood.

The first group demonstrated not only significant short-term gains--higher I.Q. scores one year into the program, for example--but long-term gains as well. About two-thirds of them graduated from high school, compared to 50 percent of the control group. Similarly, whereas 51 percent of the control group had been arrested by age 19 for some crime, less than a third of the others had.

Studies of the long-term effects of the Perry program (many conducted by its operators) made a big splash when they were first published in the early 1980s. Advocates of Head Start, then a far less ambitious and costly effort than it is today, were ecstatic. Ever since, they've used the findings to argue for more federal money.

The problem is that studies of the Perry project don't tell policymakers very much about the effectiveness of Head Start. The performance of a Ford Escort is not judged by test-driving a Lincoln Continental. "These programs (such as Perry's) were conducted under ideal circumstances," writes Ron Haskins, a staff member of the U. S. House Ways and Means Committee, in an influential article in American Psychologist. It seems unwise to claim that the benefits produced by such exemplary programs would necessarily be produced by ordinary preschool programs conducted in communities across the United States."

All this is not to question the immediate gains children make when they are cared for, stimulated, and well-fed. Indeed, the relevant research shows that it's the health and nutritional components of Head Start that provide the greatest benefits.

If we're all going to be good "public investors," we must examine the rate of return of the options that compete for our limited resources--Head Start vs. school vouchers, for example--and then set priorities. At a time when evidence overwhelmingly suggests that expanding choice for poor children to attend schools that work would yield major positive results, the $2.2 billion in the Head Start budget for 1992 could have funded $2,000 school vouchers for over one million kids.

That same $2.2 billion might also produce a higher return if it were invested in welfare reform that strengthens families. Wisconsin's Learnfare program, which puts pressure on welfare mothers to keep their kids in school, has significantly improved attendance for a third of the children in the program, an exceptionally good success rate.

Even returning the $2.2 billion to the taxpayers might be an option with more lasting benefit than Head Start, if the result is more jobs and less poverty in a healthier economy.

In any event, recognizing and employing more promising alternatives cannot happen if the hype and misconceptions about Head Start persist in preventing thoughtful analysis.