WASHINGTON AND WESTON, FLA.

Even school-choice skeptics are beginning to concede that providing families with additional options improves the academic performance of those youngsters who change schools. But what of students who stay put? A common worry about charter schools, vouchers, and other school-choice strategies is that they will harm those "left behind."

Evidence from a recent Manhattan Institute study, the Education Freedom Index, suggests this is not so, that a wider range of viable education options improves learning for choosers and nonchoosers alike. Manhattan's new study gauges the extent of education choices currently available to families in each of the 50 states. It includes indices of the availability of charter schools, subsidies (such as vouchers and tax credits) for families choosing private schools, deregulation of home-schooling, and two kinds of choice within public education itself.

The top-ranking states include Arizona, which leads the nation in charter-school options; Minnesota, which pioneered public school choice and also offers tax credits and deductions for private school expenses; and Wisconsin, which is the home of the nation's first publicly funded voucher program. Trailing on the list are Hawaii, West Virginia, and Nevada, which offer few charter schools, heavily regulate home schooling, and have no interdistrict public school choice, let alone financial aid for students opting for private schools.

The fact that states differ in the amount of education freedom is no surprise. Yet, a more striking finding is that students have higher test scores in states that offer more school choices to families than do youngsters in states with less choice – even after controlling statistically for family income, race, per pupil spending, and class size.

A comparison of Texas and South Carolina shows how much difference choice in education can make. The two states have many similarities: Both are Southern states with comparable family incomes that spend about the same amount per pupil, have kindred pupil-teacher ratios and equally large minority populations. Yet, Texas regulates home schooling less onerously, offers more public school choices, and has many more charter-school options than South Carolina.