With both presidential candidates touting their versions of it, and many cities and towns experimenting with it, school choice is flowing into the mainstream of American education.
But choice should not become an undifferentiated flood. The quality of teaching and learning will be enhanced by a wider range of options. When it comes to the use of vouchers to permit parents to go outside the public school system, however, a clear line has to be drawn. That line stops short of using public funds for a parochial education.
It's true that church-supported schools are often a convenient and relatively affordable alternative for many families. They may offer better discipline and stronger scholarship than the local public schools. But they also include instruction in religious teachings as well as academic subjects. Public funding for them, as distinct from secular private schools - though disguised by vouchers - collides with the constitutional principle of church-state separation.
The argument that the educational needs of children should override church-state concerns is short-sighted. A firm barrier against using state money for religious educational purposes is in the interest of all.
Still, parochial schools are becoming entwined in public funding controversies. New York Mayor Rudolph Giuliani wants to take up the offer of the city's Roman Catholic archdiocese to open its classrooms to some of the children the public schools don't have room for.
Cleveland is permitting parents to use public vouchers to pay tuitions at private schools, including religious ones. The program is driven by the distressed state of the city's public education system.
In tiny Chittenden, Vt., some parents want to stretch the long-standing practice of "tuitioning" local students out to neighboring high schools, both public and private, to include a nearby Catholic school as well.
The issues raised by such experimentation will eventually land in federal court, where the traditional constitutional line should again be drawn. Vouchers for use at private schools may have a limited role to play in opening American education to increased competition and diversity. But they shouldn't be allowed to chip away at the church-state "wall."