In the past five months, three major reports have been released showing that charter schools performed more poorly than public schools on the same tests. The most recent of them, issued this month by the Education Department, presented a re-analysis of data from the National Assessment of Educational Progress comparing outcomes for charter and public school students on these national exams. It echoed the NAEP findings released in August by the American Federation of Teachers. Yet another report, released reluctantly by the Education Department this fall, looked at state exam data in five states and came to the same conclusion.

What are we to make of this? Proponents of charter schools say that we don't have enough data and that the schools have not existed long enough to be judged. Opponents say three strikes and you're out.

My own view is that there are important public policy lessons to be learned from a reform movement that was promoted as the answer to a failing public school system, and that cannot, 14 years later, keep pace with that system. As a researcher who has studied charter school reform in six states, I believe we should not interpret the recent reports as an indictment of individual charter schools. Rather, they should alert policymakers to the hazards of building an educational reform movement on top of untested rhetoric about market forces and public schools.

I have seen some excellent charter schools, with well-trained educators and solid curriculums. They tend to be in more middle-class communities, where private resources augment the low level of public funding that charter schools receive. I have also seen charter schools run by people who collect the public funding while providing minimal services for low-income students who have few other options. And I have seen a lot of the charter schools that fall somewhere in between -- not stellar, not awful, but no better than the public schools nearby.

With such variation at the grass-roots level, it's not fair to say that all charter schools are failures. Yet clearly we have enough evidence to suggest that the free-market ideals that fueled this reform movement are at best misguided and at worst harmful to the most disadvantaged students. It was this rhetoric that persuaded lawmakers in 42 states to pass laws establishing some 3,000 charter schools, which have enrolled nearly 700,000 children. It is this set of principles that lawmakers must reconsider.

To better understand why so many policymakers entrusted the education of so many children to an untested reform movement, we need to look back to the 1990s, when the allure of the market dominated most public policy decisions. Smaller government, privatization of public services, less regulation, freer markets and more competition became the mantra of those who took classical economic theories to the extreme.

In the field of education, politically conservative reformers and their well-funded think tanks passionately advocated free-market philosophy as the best way to force public schools to improve. They called for charter school laws to deregulate what they saw as an overly regulated public education system. They wanted more public money in the hands of private and independent school operators. They claimed that these more autonomous schools could do a better job with less money and thus force the public schools to either compete or go out of business.

This did not start with charter school advocates. Proponents of vouchers for private schools have made much the same claim since the 1950s. But what the bipartisan supporters of charter schools did not consider was that there was scant evidence to suggest this reform would actually improve public education. And in one statehouse after another, the free-market advocates pushed for charter school laws with no caps -- or high ones -- on the number of charters to be granted, and with the greatest degree of autonomy for the charter schools. Ultimately, the focus of the free-market reforms was to increase the quantity of charter schools while paying little or no attention to their quality. This is educational deregulation at its worst.

Now the national test scores support what state-level studies of charter schools have suggested for years -- that free-market principles are not what is needed to improve public schools. Carrying out market-based school reform on the cheap requires people with the experience to educate children, the business acumen to run an autonomous institution, the political connections to raise the private funds needed to keep the school afloat, and the ability to forsake their personal life to work six or seven days a week, 12 to 14 hours a day. It turns out that there are a limited number of people who can or will do charter school reform well. Thus, most charters schools hire younger, less experienced teachers and have high rates of teacher and administrator burnout and turnover.

In this decade of growing free-market disillusionment, policymakers should amend state laws to better support the high-achieving charter schools and close the rest. And I hope they will also remember the hard lesson learned from this reform: that free markets in education, like free markets generally, do not serve poor children well.

The writer is a professor at Teachers College of Columbia University and editor of "Where Charter School Policy Fails."

Published Friday, Mar. 10, 2006