Chancellor Joel Klein’s strategy of empowering principals while holding them more accountable for results helped struggling schools get better. But his A to F grading system is “deeply flawed” and needs improvement.

That’s the message of a new, incredibly detailed report from the New School’s Center for New York City Affairs.

The report is the result of a study of hundreds of schools, including in-depth interviews with principals and school visits. The authors focused especially on the Bronx’s District 7.

The report is being released this morning at a panel discussion featuring Board of Regents Chancellor Merryl Tisch; the Department of Education’s accountability chief Shael Polakow-Suransky; John Garvey, until recently the City University of New York’s liaison to the public schools; and MS 223 principal Ramon Gonzalez.

We’ll have more details after the panel. For now, here’s the report: