BALTIMORE — Felton Barner retired in late 2007 after spending 30 years in the information technology industry. But the 60-year-old Columbia, Md., resident didn’t stay retired for long. Earlier this year, Barner decided to pursue his lifelong interest in photography; he opened an art gallery business in May.

Peter Van Buren, too, was ready for a new start after a 25-year career in wine sales. Finding a company that matched his passion in promoting environmental sustainability proved challenging, though. So Van Buren and two partners founded the Baltimore home energy company TerraLogos Green Home Services in 2006. He was 53 at the time.

For years after the dot-com boom, the 20-something upstart has been held up as a model of entrepreneurial spirit. But contrary to such popular belief, it is the baby boomer generation — 55- to 64-year-olds — that has the highest rate of entrepreneurial activity, according to a recent study by the Ewing Marion Kauffman Foundation, a Kansas City, Mo., nonprofit group that encourages entrepreneurship.

The study predicts the U.S. might be on the verge of an entrepreneurial boom because of a growing, aging population.

“I’m pleased to see that I’m not alone in looking out there and realizing the Elvis Costello (lyrics), ‘Don’t bury me ’cause I’m not dead yet,’ ” Van Buren said. “I’ve got a lot of life to live and a lot of living to offer, and I’ve got a lot of things to offer. The idea that I would go away quietly is ridiculous.”

With baby boomers living healthier and longer lives, they are no longer following traditional retirement paths and instead seeking second and third careers. Part of that wave reflects a shift from lifetime jobs with long-term employment falling for people ages 35 to 64 years old during the past 50 years, according to the study.

Besides, older Americans have the experience, skills, contacts and other resources to pursue entrepreneurial opportunities.

“They don’t run out of ideas when they retire,” said Dane Stangler, a senior analyst at the Kauffman Foundation who wrote the study.

Starting a business during the worst economy since the Depression could have deterred most entrepreneurs, but Barner, feeling restless in retirement, decided it was the right time.

“This is now or never, despite the doom and gloom that was forecast all over the place,” Barner recalled. “I really can’t wait for things to get better. I need to do it on my timetable. I’ll take the risk. At least I know I tried it.”

Barner, who began shooting pictures in the 1970s, dug up his old film and manipulated the coloring and texture to create new renderings, which received positive feedback and were featured at a local gallery. That led Barner to open ReIMAGE Galleries.

The gallery sells Barner’s artwork and also provides photographic services, such as digitizing work by other artists. Barner is working out details to lease display space for other artists.

So far, Barner said being his own boss has been rewarding, if hard work.

“The business is moving slowly, but things do take time and patience is required,” he said. “The eternal battle is trying to make it a successful financial operation versus having fun pursuing the craft of photography — the businessperson versus the artist. (They are) two hats that must be worn if anything is to come of it.”

Judah Ronch, interim dean of the University of Maryland, Baltimore County’s Erickson School, which focuses on aging issues, is not surprised by the risk-taking nature of baby boomers, whose childhoods in the 1960s and 1970s have helped form their attitude toward growing old.

“There is a sense of ‘I will not age according to the stereotypes,’ and part of that is ‘I’m not going to retire,’ ” Ronch said. “They’re approaching aging as the next step of development as opposed to the next period of decline.”