Private Schools Are Closing the Achievement Gap

Published April 1, 2005

A recent analysis of national test score data suggests private schools do a better job than public schools of closing the achievement gap between black and white students as they progress from fourth to 12th grades.

That was true despite the fact that the disproportionately higher dropout rate among African Americans in public schools tends to remove poor performers from the test-taking population of public school seniors.

Closing the achievement gap between black and white students has been one of our nation’s overarching goals for half a century. However, there remains a gulf of more than 200 points between the SAT scores of white students and black students, and black children trail their white peers by significant margins on every subject tested by the National Assessment of Educational Progress (NAEP).

Private Schools Do Better

One aspect of the very familiar achievement gap, however, is almost universally unknown: how it differs between public and private schools. This disparity can be documented by using a U.S. Department of Education database to compute the average NAEP test score differences between black students and white students in both public and private schools. The results appear in the accompanying table.

As the table shows, there is a sizeable achievement gap between black and white fourth-graders in both public and private schools. It is also clear the private-sector achievement gap is narrower in the 12th grade than the fourth grade for all of the core NAEP subjects. Public schools, by contrast, see a larger gap in both writing and mathematics at the 12th-grade level than at the fourth.

Averaged across subjects, the public school racial achievement gap is virtually unchanged between fourth and 12th grades. By contrast, the gap in private schools is an average of 27.5 percentage points smaller in the 12th grade than the fourth.

Statistics Understate Difference

The achievement gap closes faster in private schools not because white private school students lose ground with respect to white public school students as they move to higher grades, but because black private school students learn at a substantially higher rate than black public school students.

Still, the comparison in the table is arguably unfair to the private schools.

Economist Derek Neal has found that black students attending urban private schools are far more likely to complete high school, gain admission to college, and complete college than similar students in urban public schools.

Similarly, in a study comparing graduation rates of all Milwaukee public school students (of all income levels) with those of the low-income participants in the city’s private school voucher program, Manhattan Institute Senior Fellow Jay Greene found the voucher students were more than one-and-a-half-times as likely to graduate as public school students.

White/Black NAEP Achievement Differences for Public and Private Schools
NAEP Test Subject Year 4th Grade Gap (Public) 12th Grade Gap (Public) Percent Difference* Between 4th and 12th Grade Gaps (Public) 4th Grade Gap (Private) 12th Grade Gap (Private) Percent Difference* Between 4th and 12th Grade Gaps (Private)
Reading 2002 29 25 -13.8 27 14 -48.1
Writing 2002 20 23 15.0 22 18 -18.2
Math 2000 30 33 10.0 28 23 -17.9
Science 2001 35 31 -11.4 27 20 -25.9
Source: NAEP Data Tool,
* Negative number indicates a 12th grade black/white score gap that is smaller than its corresponding fourth-grade gap.

More remarkable still, Greene found this to be true even when he compared the voucher students with those attending Milwaukee’s elite group of academically selective public schools.

This higher graduation rate in private schools is not only a boon in itself; it also casts the private sector achievement gap reductions in an even more favorable light. Dropouts tend to be poor performers academically, so when they leave the test-taking population, the average test scores of the remaining students usually rises.

This dynamic should generally improve the test scores of public high school seniors, which means public schools have an even worse impact on the test score gap than the statistics show.

Andrew J. Coulson ([email protected]) is senior fellow in education policy for the Mackinac Center for Public Policy. This article is based on a study originally written for the Web site.

For more information …

See Derek Neal, “The Effects of Catholic Secondary Schooling on Educational Achievement,” Journal of Labor Economics, vol. 15, no. 1 (1997), available online at

See Jay P. Greene, “Graduation Rates for Choice and Public School Students in Milwaukee,” School Choice Wisconsin, September 28, 2004, available online at