D.C.’s faltering (or failing, according to some circles) public school system thought it found a solution in publicly-funded, privately-managed charter schools. Independent governing boards run these alternative educational institutions, making decisions on everything from curriculum to allocation of the taxpayer dollars funneled into these sometimes controversial schools. The novel public-private system seemed an attractive option for a city struggling to put enough textbooks in the classroom, but according to a study published last month by Stanford University’s Center for Research on Educational Outcomes (CREDO), charter schools may not be the answer, after all. In fact, D.C. charter schools appear to produce the same results as traditional schools, which in a city of many failed educational reforms is not exactly hopeful.

The CREDO report recognizes a “robust” and growing national demand for charter schools among parent and local community groups, but is wary about the amount of praise directed the schools’ way. The report, the first comprehensive study of its kind, compared charter and traditional schools’ academic performances in state achievement tests in 15 states and D.C., and found a wide variance across the country. It found higher math and reading gains in 17 percent of charter schools, mixed or inconsequential differences in 46 percent (including D.C. charter schools) and significantly lower gains in the remaining 37 percent.

For Florida, Arizona, Minnesota, New Mexico, Ohio, and Texas, all of whose charter schools fall in the latter category, these results prove troubling. Miami-Dade County, for example, counts 24,000 students enrolled in charter schools. In other words, that could be 24,000 students who would have fared better in the traditional public school system.

But there may be a fix to this dilemma: The study found that states without caps limiting the growth of charter schools presented higher achievement scores, as did those with a lower number of charter school authorizers. Perhaps that 37 percent can redeem itself by making its state educational policies friendlier to the conditions CREDO attributed to higher achievement.

And all is not lost. Some positive results in the study concluded that low-income students received more benefits from charter schools than traditional schools, as did those in English Language Learner programs. For a city like D.C., where one in five residents lives in poverty, according to the Census, charter schools may not produce broader higher achievement, but they may help those who need help most.