In an article published in the Spring 2013 issue of the Journal of Policy Analysis and Management, University of Arkansas professor Patrick J. Wolf and his colleagues examined student performance data for students who were selected and students who were denied a voucher as a result of a lottery selection process.  Wolf et al concluded,

Because the program was oversubscribed in its early years of operation, and vouchers were awarded by lottery, we were able to use the “gold standard” evaluation method of a randomized experiment to determine what impacts the OSP [Opportunity Scholarship Program] had on student outcomes. Our analysis revealed compelling evidence that the DC voucher program had a positive impact on high school graduation rates, suggestive evidence that the program increased reading achievement, and no evidence that it affected math achievement. We discuss the implications of these findings in light of recent policy developments including the reauthorization of the OSP and the enactment or expansion of more than a dozen school voucher or voucher-type programs throughout the United States in 2011 and 2012.

To summarize, voucher recipients had higher graduation rates and reading scores.  There was no evidence of higher math scores.

The Opportunity Scholarship Program has served low-income families in the District of Columbia since 2004.  To learn more about this and other school voucher programs, read School Vouchers: From Friedman to the Finish Line.