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What Works Clearinghouse

What is the study about?

This study examined the effects on academic achievement of offering students enrollment in the Promise Academy charter middle school. The school is sponsored by the Harlem Children’s Zone®, which combines reform-minded charter schools with a web of community services designed to provide a positive and supportive social environment outside of school.

What did the study report?

Students offered enrollment in the school had higher math test scores in sixth, seventh, and eighth grades than the students not offered enrollment. By the time they were tested in eighth grade, the effect size for the math test was 0.55. The WWC interprets this as equivalent to moving a student from the 50th to the 71st percentile.


Dobbie, W., & Fryer, R. G., Jr., (2009). Are high-quality schools enough to close the achievement gap? Evidence from a social experiment in Harlem. (NBER Working Paper No. 15473). Cambridge, MA: National Bureau of Economic Research.

This quick review was prepared for the WWC by Mathematica Policy Research under contract ED-07-CO-0062.