School Friendships, Upward Mobility, and Future Incomes

Schools can foster friendships and other relationships across class lines that boost upward mobility and raise the future incomes of low-income children. That’s a key finding of a massive study led by Harvard economist Raj Chetty that analyzed 21 billion Facebook friendships, encompassing 84% of U.S. adults between ages 25 to 44.

The study calls these cross-class relationships economic connectedness; sociologists call them class-bridging social capital. The researchers found economic connectedness to be the best predictor to date of upward mobility for low-income children—more than school quality, job availability, family structure, or a community’s racial makeup.

When low-income children grow up in a community with economic connectedness resembling that enjoyed by typical children of high-income parents, it increases their future incomes on average by 20%—equivalent to attending about two years of college.

Cross-class friendships have a snowball effect. Teachers, coaches, and other mentors and supporters establish relationships with young people that shape their aspirations and behaviors and show them worlds and opportunities they’ve not imagined. Outcomes for low-income children are better when they have higher-income friends.

Cross-class friendships are created by a roughly equal blend of two factors. The first is exposure to higher-income individuals in settings like schools, work, or religious organizations. The other is engagement with individuals different than ourselves that overcomes our natural tendency to associate with those similar to ourselves.

In short: Exposure + Engagement = Economic Connectedness

Schooling is one of the institutions that can prevent or promote cross-class friendships. 

Large high schools usually have a smaller share of cross-class connections, or worse “friending” bias, with less mixing and more same-class student groups. A school’s academic tracking can produce higher friending bias and fewer cross-class friendships even in socioeconomically diverse schools. Additionally, high Advanced Placement enrollments and gifted and talented classes limit cross-class friendships in racially diverse schools. Finally, fewer cross-class connections in college are associated with greater racial diversity and higher student enrollment.

But friending bias can be overcome. For example, colleges and large high schools can assign students to smaller and diverse “houses” or “hives.” They can organize cafeterias, libraries, science labs, extracurricular activities, and dorms to create cross-class groupings.  

Public charter schools are another example.

My colleague Jeff Dean analyzed the 214 charter high schools in the Chetty study’s database. On average, they perform better than 80% of traditional public schools on friending bias, raising research questions like whether the autonomy and community-building aspects of public charter schools contribute to this and how other public schools can duplicate these features.

On a personal level, my cross-class friendships took root and developed in three places when I was growing up in Cleveland, Ohio during the late 1950s and early 1960s.

One was the local YMCA, especially its two-week away-from-home summer camp. It was unusual for a Catholic school student like me to go to the Y rather than the Catholic Youth Organization, or CYO. But my parents (neither had college degrees) said I should be with kids and adults I didn’t know. That sounded good to me.

Another was the Northeast Ohio Red Cross headquarters in downtown Cleveland, where I was a youth volunteer and school delegate. A third place was St. Joseph Catholic High School on Cleveland’s east side.

At these places, I met young people and adults from five Northeast Ohio counties with different racial and ethnic backgrounds and income levels. Camp counselors and staff included laborers, teachers, coaches, nonprofit leaders, lawyers, and doctors.

I made cross-class friendships with many individuals, opening my eyes to personal and vocational aspirations that I wouldn’t have imagined staying in my cheerful but small Italian-American neighborhood. I cherish these memories and remain friends with some I met back then.

Cross-class friendships are critical in expanding economic opportunity, improving life prospects, and advancing human flourishing. Schools that foster them put young people on a path to social and economic well-being, informed citizenship, and civic responsibility.