As Pennsylvania legislators debate several voucher proposals, the center's finding is being cited by opponents.
Voucher supporters dispute the conclusion and say other factors, such as school safety and parents' desire for more educational options, justify the proposed laws.
Nationwide, there are seven voucher programs; two cover entire states; the rest, specific counties or cities. A statewide Florida program was struck down by the courts in 2006.
Legislation proposed in Harrisburg would give state money to low-income students, including those already in private schools, to help pay tuition.
Several other voucher proposals have also been put forward. The legislature recessed for the summer without acting on the measures.
In New Jersey, the focus has been on a proposal giving tax credits to businesses donating money to help low-income students in low-achieving schools attend schools outside their districts.
At several recent legislative meetings airing voucher plans, critics mentioned the Center for Education Policy study or similar reports.
At a House Education Committee informational meeting late last month in Philadelphia, for example, Rep. Mark Longietti (D., Mercer) said, "If we're going to spend lots of money . . . we need to see results. . . . Why should we invest in a program when in other states, the data's coming back and saying, 'It's not working?' "
Voucher advocate Matthew Brouillette, head of the conservative Commonwealth Foundation, responded in an interview last week after taking part in a state Senate Democratic Policy Committee school-choice discussion.
"Academic gains is certainly a big driving component of this, but at the end of the day, this should be about parents choosing what they believe is a better or a safer school for their children," he said.
Brouillette cited other research showing academic gains for voucher students. "At the very least, [vouchers in other states have] saved a ton of money and we've allowed parents to have an alternative to their assigned public schools," he said.
The center's study, released in late July, looked at research since 2000 on public voucher programs. It said: "While some studies have found limited test score gains for voucher students in certain subject areas or grade levels, these findings are inconsistent among studies, and the gains are either not statistically significant, not clearly caused by vouchers, or not sustained in the long run."
Robert Enlow, head of the pro-voucher Foundation for Educational Choice, disputes that, saying studies of privately funded voucher programs not included in the report showed voucher students making some academic gains.
He added that competition from voucher programs had pushed public schools to improve and some studies showed higher voucher-student graduation rates.
The center reported those findings but said they were less conclusive than its main one, "because they were supported by fewer studies, could not be clearly attributed to vouchers, or were based on self-reports."
Whoever is right, the voucher movement remains fueled by parents who believe their children are trapped in substandard public schools and who want an alternative.
At the Senate Democratic hearing, Annemarie Smith of Northeast Philadelphia, a divorced mother of two, told the panel the middle school her son is to attend in the fall "has a horrible reputation." He is on the waiting list for several charters, she said, and "I can't afford Catholic school. . . . Somebody has to help me."
No one offered an immediate solution, though some panel members talked to Smith after the meeting. "The silence is deafening," Brouillette said, "and that is the problem."
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