Trading spaces.

In late January, President Bush signed a giant spending bill containing one tiny but explosive provision: a five year, $14-million program to provide private-school vouchers to the children of the District of Columbia. With that, Bush launched an aggressive new phase of the decade-long battle over the voucher issue. Previous small experiments in places like Milwaukee and New York have relied on private or state funds. The D.C. program, set to begin in the fall, puts the federal government directly into the voucher-funding game. And while vouchers may be too controversial with swing voters for Bush to openly talk about them in this year's presidential race, the fact that his administration negotiated so hard for the D.C. program suggests that we're likely to see a big push for vouchers in any second Bush term.

Vouchers are one of those subjects for which both sides marshal compelling, if ultimately unsatisfying, arguments. Their opponents argue that to date, studies have not found much evidence that existing voucher programs have yielded improved achievement; that, unlike the public education system, private schools aren't required to test all their students, as public schools now are, and hence aren't accountable for results; and that whatever extra money is available ought to go first to improve existing public schools. Voucher proponents counter that there's no evidence that vouchers do any harm, some indications that they improve minority student performance, and that after 20 years of only slightly successful attempts to reform urban schools, it simply is not fair to keep poor kids waiting around in visibly failing schools for reforms to kick in.

What's needed is a way to cut through this Gordian knot--with a voucher program that provides poor kids with real choice, has a demonstrated record of success and avoids the pitfalls that make liberals skeptical. As it happens, such a program has been underway in Missouri for years.

Beginning in 1983, as the result of a court desegregation order, inner-city St. Louis schoolchildren were allowed to cross city-suburban boundaries to fill empty seats in wealthier suburban school districts, the state paying a fee for each such child to the suburban schools that accept them. This program, called the St. Louis Voluntary Interdistrict Choice Corp., was more politically popular than most similar busing programs around the country, and the state legislature voted to keep it going in 1999, when the desegregation order expired. Since then, the program has been voluntary--neither students nor school districts have to participate if they don't want to--and the state pays public schools $6,081 per student to accept out-of-district kids. Participation by even the best suburban schools is widespread. Schools in Clayton, one of St. Louis' tonier suburbs, accept 500 students from inner-city St. Louis. Nor are the transfers all outward; last year, 556 suburban St. Louis students transferred to attractive magnet programs in the city.

The St. Louis transfer program may qualify as the most studied education experiment in the country. Here are the findings: Although students get off to a slow start in their new schools, by the time they graduate they score significantly higher on achievement tests than do those who stay in urban schools. And here's the clincher: Inter-district students graduate from high school at twice the rate of their counterparts back in the city.

The St. Louis program has been so successful that you might think it would be perfect for D.C. Mayor Anthony Williams and the Bush administration to try in the district. Indeed, voucher proponents who say that poor black parents deserve the choices available to affluent white parents, need only recall that for years some wealthy white D.C. parents have been paying fees to send their kids to better schools across the district line in Montgomery County, Md. Yet the D.C. government and the Bush administration specifically rejected this model city-suburb choice program literally in their own backyard.

Why? Obviously, memories of the busing fiascos of the 1970s might make any politician leery of supporting a program that empowers poor inner-city blacks to attend suburban schools. But a lot has changed in 30 years. Most public schools in the D.C. suburbs are strikingly diverse, with African Americans as well as immigrant kids from many different backgrounds. And as the Missouri example shows, suburban parents don't seem to mind voluntary city-suburb choice programs.

In any event, it was not fear of white backlash that deflected the Bush administration and D.C. officials from the city-suburb option. The real reasons were hardly more edifying. Mayor Williams has been marketing vouchers as a way to revitalize D.C., and shipping kids to the suburbs would undermine such a rationale. Meanwhile, the Bush administration has been using the D.C. experiment to garner support from its conservative base, which sees vouchers as part of a larger agenda of privatizing government; vouchers for suburban public schools don't advance that agenda.

But while a cross-district voucher program might not serve certain narrow political ends, it does meet the biggest problem confronting private school vouchers: the scarcity of classroom seats. In D.C., as in many other cities, affordable parochial schools have a limited number of openings for new students--only 1,300 this year, while good D.C. private schools charge upwards of $20,000 a year in tuition and have long waiting lists. Some entrepreneurs will doubtlessly start private schools to capture the voucher market. But if the city's experiment with charter schools is any indication, such startups are as likely to he shabby fly-by-nights as caring havens. And while bad charter schools can--and sometimes are--shut down by the city, there's no mechanism in the new voucher law to keep dysfunctional private schools from continuing to receive public funds.

D.C.'s existing private schools can probably absorb the small number of students--1,700--who will receive vouchers under the new choice experiment. But voucher proponents aren't shy about wanting to expand the program vastly. The urge is understandable: There are 65,000 students in D.C.'s public schools, a large percentage of whom are stuck in failing schools. The only way to provide most of these children the choice of attending truly better schools anytime soon is through voluntary inter-district choice--the route D.C. and the Bush administration rejected. Harvard professor emeritus Chuck Willie, an advocate of school choice for poor urban students, observes that the D.C. voucher plan "sounds like containment for poor black kids" Willies right. A program to rescue kids from failing schools should be guided by education policy, not containment policy.

Richard Whitmire writes about education issues for the USA Today editorial page.