David Fenton, second from left, is selling Fenton to new owners, Craig Leach, left, and James Marcus, right. Mr. Fenton will become chairman as Bill Werde, third from left, becomes chief.

One of the first agencies devoted to handling communications efforts for causes, nonprofit organizations, charities, foundations and activists seeking social change — a specialty that is now thriving — is being sold by its founder and longtime leader, David Fenton, to investors who are forming a holding group for agencies of that kind.

The agency, named Fenton, is getting new leadership along with its new ownership; the changes are to be announced on Wednesday. Mr. Fenton, who was chief executive, is taking a different role, as chairman, and he plans to devote more time to working on efforts to counter global climate change. To succeed Mr. Fenton as chief executive, the agency is hiring Bill Werde, who was most recently editorial director of the music trade publication Billboard.

The new owners of Fenton are Craig J. Leach and James Marcus, who are the principals of Collegium, a holding group specializing in agencies in the category known by terms like cause marketing, cause-related marketing, prosocial marketing and purpose marketing. Such agencies provide services like advertising, public relations, fund-raising, digital media, event marketing, mobile ads and social media.

When Mr. Fenton opened the agency in 1982, as Fenton Communications, “everyone said I was nuts, and I was,” Mr. Fenton, 62, said during a recent interview.

“At that time, environmental organizations, human rights organizations, health groups didn’t even have press secretaries,” Mr. Fenton recalled. “The biggest change to me over the years is that there is now a market for what we do, a whole big industry in this. And it’s only going to continue to grow.”

Fenton has 60 employees who work at a headquarters in New York and offices in Los Angeles, San Francisco and Washington. Current and recent clients include the Corporation for Battery Recycling, the Environmental Defense Fund, the Ford Foundation, the Harlem Children’s Zone, the Robert Wood Johnson Foundation, Save the Children, the Sierra Club and the Wikimedia Foundation.

Around 20 percent of the agency’s work, by Mr. Fenton’s estimate, is for clients that are for-profit marketers, helping them in realms like corporate social responsibility and sustainability; examples of those clients are Johnson & Johnson and Unilever.

Mr. Marcus, 48, whose title at Collegium is partner, has served as an adviser to Fenton for more than a decade and led a Fenton division, Fenton Studios, that produces video content for clients. Mr. Leach, 55, whose titles at Collegium are partner and chief executive, is also chief executive of a unit of Collegium, Graham-Pelton Consulting, which helps universities, hospitals, social service agencies and environmental organizations with fund-raising and management tasks.

Financial terms of the deal by which Collegium is acquiring Fenton are not being disclosed. The purchase price in many such transactions is the equivalent of a year’s revenue; Fenton has revenue of about $11 million. Mr. Fenton has agreed to remain at Fenton for five years.

It was Mr. Marcus who brought Mr. Leach and Mr. Fenton together. “We at Fenton wanted someone who had an appreciation for the company, a little company but a company that’s had an impact,” Mr. Marcus said.

“Fenton is well known, but there are still a lot of people who don’t know about it,” he added. “We’re going to take what’s right about Fenton and join more battles on the good side.”

Mr. Werde, 41, said he initially met with Mr. Fenton “because I wanted to build a platform that could make sustainability a little more accessible to the consumer.” The music industry’s environmental policies was a subject he followed while directing editorial coverage at Billboard. Asked how that turned into Mr. Werde joining Fenton, he replied, “I went to David and gave him my pitch, and he said: ‘I love it. Now can I tell you what I need?’ ”

“I’m hoping my music background may have particular relevance to the cause space,” Mr. Werde said. “Outside of a few stalwarts like Bruce Springsteen, and some younger artists such as John Legend and J. Cole, music has somewhat abdicated the throne of political relevancy. It’s really time for that to evolve again.”

It is also “crucial that underfunded cause organizations and activists have access to the same sophisticated communications and media approaches as well-funded opposing forces,” Mr. Werde said. That echoed an earlier remark of his about how, in his first meeting with Mr. Fenton, “David told me he had started the firm because the bad guys always had publicists and the good guys never did.”