It's getting harder every day to be an informed and compassionate opponent of vouchers. A new book called "Choosing Equality" just may spell the end of my opposition.

There are two good reasons not to give poor families public money to give them choices beyond their neighborhood school: It might hurt public schools, which desperately need careful attention and wisely used resources. And it might be unconstitutional because it could involve government support for religious schools.

The courts will decide the second question. And despite the recent injunction in Cleveland, vouchers seem likely to prevail -- on the grounds that aid to families, rather than aid directly to religious schools, is permissible.

As the Heritage Foundation quotes Harvard Law's Laurence Tribe on this subject: "Any objection that anyone would have to a voucher program would have to be policy-based and could not rest on legal doctrine. One would have to be awfully clumsy to write voucher legislation that could not pass constitutional scrutiny. . . . Aid to parents . . . would be constitutional."

That leaves the question of whether vouchers are good public policy. Here is where Joe Viteritti's new book may have pushed me over the line. Viteritti, director of the Program on Education and Civil Society at New York University, discussed his book -- subtitled "School Choice, the Constitution and Civil Society" -- recently at the Brookings Institution.

Viteritti acknowledges that, in their first incarnation -- in the 1950s, championed by Milton Friedman -- vouchers were a market-driven idea frankly anticipating the end of public education. Forty years later, "the second generation," he says, is "not a market model but an opportunity model. . . . What you see now is money directed at poor kids, defined by need."

The powerful argument for this is simple fairness. Families of means can make choices about education. They move to neighborhoods with good schools. They can send their kids to private or parochial schools. Poor parents have no such choices. If their local schools are failing, their kids are trapped. And far too many of our schools are failing: This is the challenge that demands our attention. The question is, can a voucher program coexist with the struggle to improve our schools?

Viteritti argues that, properly designed, it can and, to be fair to all, it should. His research, based on the limited evidence so far -- from public programs in Cleveland and Milwaukee and a few privately funded voucher programs -- indicates that fears of the best students being "skimmed" from public schools are exaggerated. Preliminary indications are that student performance is strengthened. And the clearest conclusion of all is that parents love them: "They like the quality of the education, the safety of the school, the value structure of the school and the opportunity for parent involvement."

As for what the public thinks, polls show ambivalence -- except among particular groups, whose support is striking: A 1997 Gallup Poll put approval from blacks at 72 percent and from urban residents at 59 percent. The strongest backers of all are poor minorities. You can't miss the fact that these are the people vouchers would help.

Overall, public opinion is shifting gradually toward vouchers, according to education expert Diane Ravitch, who suspects this may be attributable to despair over urban schools. I like to think that many city schools seem finally to be beginning to pull themselves from the swamp.

States are instituting more rigorous standards, hiring better teachers and giving them more training, holding schools and teachers accountable and making results public. It's just a start. But it has strong support from the public. National Public Radio's recent poll indicated that three out of four respondents were willing to have their taxes raised by at least $200 a year to improve public schools.

Could vouchers be a suitable companion to these improvements? Viteritti belongs to the camp that says competition can help, but only if we use vouchers in conjunction with broad reforms, including a commitment to close failing schools. Even so, he acknowledges: "We don't know what the effect of competition is going to be, because we haven't really tried it."

As a parent of an urban public high-school student, I flinch at anything that drains resources from public schools. But I have choices. Keeping them from others because of a vague threat seems increasingly hard to justify.

I've still got plenty of questions. But giving vouchers enough of a test to provide more answers begins to look like the right thing to do.