Education reform efforts have focused almost exclusively on improving big-city public school systems. The problems of Atlanta Public Schools are well known to everyone. What is much less understood is that many of our affluent suburban districts are also badly in need of improvement.

Suburban school districts may be performing much better than their urban neighbors, but they are barely keeping pace with student achievement in other developed countries.

This surprising discovery of subpar outcomes in many affluent suburbs came to light as part of a large project we recently completed called the Global Report Card. We compared student achievement in virtually every one of the nearly 14,000 U.S. public school districts with the performance of students in a group of 25 developed countries. All of the results are available at www.global reportcard.org, so people can look up their own and other school districts’ results to see how they are doing relative to students overseas.

If they looked up Atlanta, they would confirm their suspicions that student achievement is dreadfully low. The average Atlanta student is performing at the 23rd percentile in math relative to students in other developed countries. That means that 77 percent of students in a typical developed country would be doing better than the average student in Atlanta.

But if they looked up Fulton, Cobb or Forsyth schools, they might be surprised to see that those districts, despite being among our most advantaged and presumably best public school districts, are struggling to do better than the average student in other developed countries.

In Fulton, the average student is only at the 37th percentile in math compared with students in our group of 25 developed countries. In Cobb, the average student is only at the 37th percentile. And in Forsyth, the average student is only at the 61st percentile.

These results are better than Atlanta’s, but they are probably below what people might expect for affluent suburbs. If students from those suburbs want to compete with students from all over the world for top-paying jobs in our increasingly globalized economy, they need to be near the top of these international comparisons, not near the middle.

It is true that reading results in these suburban districts are somewhat stronger, but math provides a more meaningful comparison. Math tests are more consistent across countries than reading, and math performance is much more predictive of economic success.

The scarcity of excellent public school districts is not unique to the Atlanta area. Of the nearly 14,000 U.S. public school districts, only 6 percent have average student math achievement that would place them in the upper third of global performance. And among the school districts serving the 50 wealthiest places with populations over 50,000 — places not so tiny as to be inaccessible — the average math percentile is only 52.

Suburban parents need to awake from their complacency. Education reform is something that is not only needed for large urban school districts. Most suburban public school districts also need to improve.

And who knows: If we get buy-in for serious reform among suburban elites, perhaps it will not only help suburban districts get better, but it may also produce the improvement urban districts have long sought.

When politically powerful and influential suburbanites get behind dramatic education reform for everyone because they think their own children need it, we may see gains that decades of lip service and half-hearted reforms have failed to produce.

Jay P. Greene is the 21st century professor of education reform at the University of Arkansas and a fellow at the George W. Bush Institute. Josh B. McGee is the vice president for public accountability initiatives at the Laura and John Arnold Foundation.