The aim was to make volunteers out of career-centered and ambitious thirty-somethings, the ones with big hearts but overflowing appointment books.

The outcome is "doingsomething," a year-old volunteer program featuring minimum time commitment and maximum flexibility to entice busy professionals to get involved in community projects.

Appropriately, the operation is run with today's executive imperative: a telephone answering machine with call-in capability.

Leaders, all with busy jobs themselves, solicit projects from the D.C. office of the Volunteer Clearinghouse, a national organization that matches volunteers with needy agencies. Then they organize groups of five to 20 volunteers to donate time on the first Saturday of every month.

So far, more than 400 volunteers have logged 10,000 hours, painting and renovating clinics, feeding the homeless and taking inner-city youths on bike rides and picnics. So successful is the venture that groups in New York, Atlanta, Seattle and Los Angeles are looking to it as a model for their cities.

It works like this:

About 20 volunteers take turns being project leaders, phoning people who have signed up for a project, making sure they attend and coordinating details.

Participants sign up for what they can do and when, checking on details via the answering machine in the Adams-Morgan home of Karen Hallerman, 28, one of three doingsomething founders.

"It's become kind of the hub of the group," said co-founder Kurt Guenther, 29, a media consultant with Greer, Margolis & Mitchell. "She and her machine are the crossroads that everyone goes through."

But in typical thirty-something fashion, the group also holds informal get-togethers immediately after their Saturday projects. There volunteers sign up for coming events, often including names of friends, which is how the group grows.

The appeal of doingsomething is its flexibility: People can volunteer just once or volunteer every month, and they can always choose among a variety of projects.

Doingsomething regulars include Capitol Hill staffers, lawyers, consultants and a host of other professionals, from ages 22 to 45.

"Even though they may have the desire, their schedules don't permit weekly volunteer commitments," said Hallerman, who is director of the career center at the Johns Hopkins School of Advanced International Studies.

Saturday, doingsomething volunteers led a canoe trip for youngsters from Sasha Bruce Youthwork, a halfway house for runaways; held a street carnival for the Sojourners Neighborhood Center in Columbia Heights, which offers meals to seniors and school programs for needy children; and took children from the Columbia Lighthouse for the Blind on a picnic.

They also staffed an American Heart Association clinic on cardiopulmonary resuscitation and painted and renovated two homeless shelters, a low-income housing project and the Washington Free Clinic.

Peter Gould, a lawyer with an L Street firm, joined the group in December and led one of last weekend's renovation projects.

"It fit the bill in the sense that I knew I wanted to do something, but I didn't know exactly what," he said.

"For many people it's a non-threatening kind of introduction to volunteering," said James Lindsay, executive director of the Volunteer Clearinghouse.

He said group volunteering is "the fastest-growing trend" in the nonprofit sector, but he also praised the fledgling doingsomething for exceptional organization and efficiency.

"Some of the groups we work with, we have to constantly contact the agencies they're working for, and call people in the group," he said. "But with doingsomething, they seem to be on top of it."

Guenther; his wife, Debra, a landscape architect; and Hallerman named the group with a variation on the ABC television series "thirtysomething," as both a joke and a pointed reminder of the "yuppified" lifestyle they and their peers lead, Guenther said.

"A lot of us who watch that show are sick of the whining," he said. "To us it's kind of an antidote, {telling us to} turn away from these insular problems. There are people out there who really need help."