From report in The New York Times:
The first national comparison of test scores among children in charter schools and regular public schools shows charter school students often doing worse than comparable students in regular public schools.
The findings, buried in mountains of data the Education Department released without public announcement, dealt a blow to supporters of the charter school movement, including the Bush administration. …
They looked at low-income children in both settings, and broke down the results by race and ethnicity as well. In virtually all instances, the charter students did worse than their counterparts in regular public schools.