Steady but moderate growth in the state's school-voucher program shows that it is addressing a need and is sized about right.

Last month's crop of applications for private-school vouchers for the next school year topped 13,000 for the first time, edging close to the 14,000-student limit put on the Educational Choice Scholarship Program by the legislature.

Most of those were from students already in the program, under which the state helps pay private-school tuition for students whose assigned public schools repeatedly have been rated in academic emergency or academic watch on the state's report card.

The number of first-time applicants, at 4,284, was down slightly from last year.

The high numbers of students who want to stay in the program are evidence that parents value it. Vouchers provide an alternative for families of children in failing public schools who otherwise wouldn't be able to afford private-school tuition.

The slight dip in new applicants this year could be a sign that public schools are improving. Vouchers are available only to students in schools that have failed state evaluations three years in a row. The number of failing schools has declined, reducing the number of students eligible for vouchers.

That's meant to be one of the primary benefits of vouchers and charter schools, after all: Allowing students to opt out of poor-performing public schools creates a competition for revenues that puts pressure on those public schools to improve.

Ideally, a voucher system wouldn't grow forever but would level out as public schools rise to the challenge vouchers present.

In Franklin County, four districts -- Columbus, South-Western, Whitehall and Groveport Madison -- have had schools troubled enough that their students qualified for vouchers. Now, only the Columbus district has schools in the program.

For now, the robust participation in EdChoice and the protests of families who have chosen charter schools should persuade Gov. Ted Strickland and Ohio House Democrats not to slash funding for these alternative programs.

Improving public schools should be a top priority for Ohio policymakers. But school choice, exemplified by charter schools and vouchers, should be part of the solution.