THE AMERICAN DREAM has long loomed as the guiding promise of life in the United States. Seeds of the idea can be seen in the country’s founding documents, but the phrase itself first emerged just under 100 years ago. In 1931, historian James Truslow Adams popularized the term in his book The Epic of America to describe a society of opportunity for all, regardless of social class.

Today, the American dream seems more a mythic ideal than lived reality. The country has been buffeted by decades of economic insecurity, with upward mobility increasingly elusive, especially for those on the lower rungs of the income ladder. That angst has been a driving force in national politics, fueling populist discontent from the left and right.

As the American dream has slipped out of reach for many, few have done more than Raj Chetty to try to understand the fading of the American dream and what could be done to change that dispiriting trendline.

A professor of economics at Harvard, Chetty has emerged as the country’s preeminent scholar of economic mobility. The 46-year-old son of Indian immigrants has established an entire research center, Opportunity Insights, focused on understanding the barriers to economic opportunity and upward mobility, and on crafting solutions aimed at helping people chart a path out of poverty.

Chetty’s work pulls on strands of earlier research from a number of his Harvard colleagues, including sociologist William Julius Wilson, who chronicled the disappearance of work in inner cities and the economic isolation it brought, and fellow economists Claudia Goldin and Lawrence Katz, who have documented the ways in which educational achievement is not keeping up with the demands of advances in technology. Most notable, however, has been Chetty’s work on the impact of “social capital” on economic mobility, building on research by Robert Putnam, who launched the issue of civic connectedness into the public conversation with his book Bowling Alone, published in 2000.

Chetty has opened the door to a dramatically more fine-tuned understanding of economic mobility by making use of “big data” — enormous datasets drawing on the experience of tens of millions of Americans — to provide a strong evidence base explaining the factors that propel economic gains or inhibit them.

While circumstances like growing up in areas of concentrated poverty, or in single-parent households, have long been associated with low economic mobility, the effects of social capital have been harder to measure. Chetty and his colleagues came up with ways to do so using data from social media companies. It has transformed our understanding of economic mobility — and fundamentally reshapes thinking about the kinds of policies we should pursue to restore the vitality of the American dream for those in poverty.

“This is the single strongest predictor of economic mobility that we or anybody else has identified to date,” Chetty says of social capital that connects low-income people with those higher in the income distribution.

The challenge, he says, is aligning incentives so there is broad support for policies that can restore the promise of the American dream to all.

“Even if you set aside issues of social justice, fairness, and so on that are obviously central, and look at it purely from a cold economic lens of maximizing GDP and growth, you still want to invest in improving opportunity in these areas,” he says of communities of concentrated poverty. Chetty thinks viewing expanded opportunity as “an economic growth policy” is part of the way to bring more people to the table, something that “ultimately lead to change on scale.”

It’s a tall order, but the insights Chetty and his colleagues have provided mean we can no longer throw up our hands and say we don’t know how to tackle the problem. The challenge is mustering the political will to do it.

I sat down with Chetty to better understand the withered state of the American dream and how to revive it at the recent WBUR Festival. To read a transcript of our discussion, click here.