Ozier Muhammad/The New York Times Occupy Wall Street protesters in Midtown Manhattan on May 1, 2012.

More than a third of the people who participated in Occupy Wall Street protests in New York lived in households with annual incomes of $100,000 or more, according to a study by sociologists at the City University of New York, and more than two-thirds had professional jobs.

At the same time, the researchers found, nearly a third of the protesters had been laid off or lost a job, and a similar number said they had more than $1,000 in credit card or student loan debt.

The report (see also below), compiled by professors at the Joseph A. Murphy Institute for Worker Education and Labor Studies, looked at the backgrounds and motivations of Occupy supporters as well  as the impact of the movement. It was based on interviews with more than 700 people at a May Day rally in 2012.

Prof. Ruth Milkman, one of the study’s three authors, said that she and her colleagues, Prof. Stephanie Luce and Prof. Penny Lewis, became interested in examining the roots of Occupy Wall Street in the fall of 2011, when the movement took off. “It was the first major protest against the growth of inequality,” she said on Monday.

The research was financed the Russell Sage Foundation and assisted by about 50 graduate students, who spread through a crowd of several thousand that gathered at Union Square and then marched down Broadway on May 1, 2012.

Some of the study’s findings were unsurprising. Many participants in the movement had been involved in previous political demonstrations, and far from being spontaneous, the Occupy Wall Street protests were carefully planned.

But the study also suggested that many Occupy participants might have been more in the mainstream than some people might have guessed. Nearly 80 percent had at least a bachelor’s degree, the authors wrote, and about half of those with bachelor’s degrees had a graduate degree.

Despite the high level of education, the researchers found that a significant percentage of Occupy participants were underemployed, with nearly a quarter working fewer than 35 hours a week.

Professor Luce characterized the protesters who had problems finding full-time work as part of an emerging demographic that some commentators call the “precariat” — educated people forced into unsteady or insecure jobs because little else is available.

“These are the kids that did everything right,” she said. “They went to school, they graduated and then they faced this very problematic labor market.”