For years, education advocates have been complaining that charter schools aren't serving all children equally because they take a disproportionately low share of English Language Learners.
That allegation has caused critics to raise questions whenever charters post higher test scores than regular public schools.
In a study last month published in the Journal of School Choice, researchers from NYU found that the schools do serve fewer English language learners. But they used more data than previous studies - by looking at both state enrollment patterns in city schools from 2006 to 2008 and Census Bureau data provided by the American Community Survey.
The two researchers found most city charters do have significantly smaller proportions of English language learners than traditional schools. They suggested that could be because many are located in low-income neighborhoods such as Harlem where most children do speak English, or because non-English speaking parents aren't as knowledgeable about applying to charters.
But the academics did find one exception in the Bronx: the Family Life Academy Charter School. Its enrollment was 35 percent English language learners during the three years' of data in the study, and its students consistently performed at high levels.
A spokesman for the city's Department of Education, Jack Zarin-Rosenfeld, said the agency wants to work with every charter school in the city to make sure they’re reaching different communities and giving families options.
"Charters that aren't doing a good enough job reaching English language learners need to adapt best practices used by district and charter schools alike," he said.