A school bus is shown in Rancho Bernardo, Calif., last month. (Mike Blake/Reuters)

Each week, In Theory takes on a big idea in the news and explores it from a range of perspectives. This week, we’re talking about school desegregation. Need a primer? Catch up here.

Richard D. Kahlenberg, a senior fellow at the Century Foundation, is author of “All Together Now: Creating Middle Class Schools Through Public School Choice” and editor of The Future of School Integration: Socioeconomic Diversity as an Education Reform Strategy.”

School integration is good for kids and for society, but adults have made achieving a diverse school system difficult. A focus on socioeconomic status rather than race could make the latest pro-integration policies more appealing.

As a political matter, many leaders have been scared to death of taking steps to racially integrate schools, given the fierce backlash against compulsory busing in the 1970s and 1980s. As a legal matter, the Supreme Court in 2007 made it harder for school districts to use race as a factor when assigning students to schools. Partially as a result of the political and legal impediments, a new report from the Government Accountability Office shows that school segregation has risen sharply in recent years.

The good news, however, is that a small but growing number of school districts — aided by critical leadership from Education Secretary John B. King Jr. — are beginning to take steps to reimagine integration in the modern era. New plans focus more on socioeconomic status than race and more on choice and incentives (such as magnet schools) than on compulsory busing. According to a recent Century Foundation report, 91 school districts and charter schools — educating 4 million students — now consider socioeconomic status in student assignment plans.

Cambridge, Mass., for example, uses a system of universal public school choice to promote socioeconomic integration. All parents choose from among a variety of magnet schools, and officials honor choices in a way to ensure that all schools have a healthy economic mix of students, as measured by eligibility for free and reduced-price lunch. In Cambridge, 85 percent of low-income students graduated on time in 2014, compared with 65 percent of low-income Boston students and 76 percent of low-income students in Massachusetts as a whole.

Building on local efforts — such as those in Cambridge, Dallas and La Crosse, Wis. — King has unleashed a flurry of initiatives aimed at promoting socioeconomic integration: a $120 million “Stronger Together” federal program to support local efforts at economic integration; the creation of a new priority in the administration’s Investing in Innovation (known as i3) program for schools and districts that promote diversity; and an increase in magnet school funding with a priority for socioeconomic diversity.

In a recent Century Foundation forum, I asked King why new federal efforts are focused primarily on socioeconomic diversity rather than integration by race. He noted that given the overlap between race and class, “places that have smart socioeconomic strategies are able to achieve greater racial diversity,” an important outcome for society. But he also suggested that socioeconomic diversity should be pursued for its own sake as well.

Researchers have long found that in raising student achievement, the socioeconomic status of one’s classmates matters even more than their race. In places like Boston, the integration of working-class white and working-class black students in the 1970s did not raise achievement. By contrast, black students saw large gains when integrated with upper-middle class whites.

Research finds that the academic benefits of integration derive not from the pigment of classmates but from being in a middle-class school environment, where peers expect to go on to college, parents are able to be actively involved in school affairs and strong teachers are more often found. Nationwide, low-income fourth-grade students in middle-class schools are as much as two years ahead of low-income fourth-graders in high-poverty schools on the National Assessment of Educational Progress in math.

Framing integration primarily in terms of socioeconomic status also has political advantages. One major lesson of the 2016 campaign has been the recognition that working-class whites feel abandoned by conventional political figures, which makes them open to demagogic appeals from the authoritarian right. Socioeconomic integration benefits Hillary Clinton’s African American and Latino voters but also Donald Trump’s white working-class constituencies. Researchers are in broad agreement that providing children with an economically and racially integrated school environment promotes social mobility in our economy and social cohesion in our democracy.

Socioeconomic integration has become the rallying cry of some of the education reformers who run charter schools. While most charters have traditionally been even more economically and racially segregated than traditional public schools (a difficult thing to be), a new generation of charter leaders is using weighted lotteries and intentional recruiting to create socioeconomically diverse student bodies.

Housing advocates have taken notice as well. In Montgomery County, Md., according to a study by Rand Corp. researcher Heather Schwartz, an “inclusionary zoning” policy that allowed low-income families to live in middle-class neighborhoods and send their children to middle-class schools cut the math achievement gap between low-income and middle-class students in half.

We’ve been trying for decades to make separate schools equal. The new movement for socioeconomic integration aims higher: to educate students from all walks of life together, as public education was always meant to do.