Anne Glickman, 34, inherited several million dollars in stock on her 18th birthday. She preferred not to think or talk about the money into her 20s because, she said, as a political activist, her wealth was a bit inconvenient.

"I felt like I was in hiding," she said.

"Here I was, an activist thinking about class and race, but I wasn't really factoring in my own personal wealth," she said. "I decided to give away a large number. It was scary, but I just had to do it." So far, Glickman said, she has given away $1.2 million.

She is part of a movement of relatively young American heirs who practice what they call social justice philanthropy, which emphasizes giving to small, local groups.

Karen Pittelman, 32, a singer in a punk band, said she inherited $3.5 million seven years ago and gave away all but $15,000. Jamie Schweser, 35, author of the novel "Tales of a Punk Rock Nothing," said he inherited $1 million eight years ago and gave away three quarters of it.

So what motivates people to give away so much of their money?

For Anne Glickman, the decision was not about trying to live an ascetic life. "I'm not an anti-materialist," she said. "I don't believe you shouldn't have a nice TV. But people said, 'What about your unborn children?' And at the time I think I was sitting on $12 million. I mean, how much do you need to raise children?"

Tyrone Boucher, 25, said he told his father he wanted to donate his six-figure trust fund to groups that work for racial equality. As part of his argument, he pointed to the growing gap between the rich and the poor. His father, he said, responded: "Tyrone, we're not really rich. There are people who have multiple homes and private jets."

"The point isn't to dis my dad," he said. "The point is, what's enough?"

Many donors said these conversations were the first they had with their parents about what it means to have money.

"It's the most taboo of subjects," said Judith Stern Peck, director of the Money, Values and Family Life Project at the Ackerman Institute for the Family in New York. "Parents don't talk about it for a myriad of reasons - because they don't want to spoil their children, because it might touch on a host of other things that are also difficult to talk about. Or perhaps because there might be contradictions between what they say their values are and what they do with their money."

Groups like the nonprofit Resource Generation offer programs and seminars for wealthy adults under 35. Participants describe the meetings as something like a support group.

"When the money was suddenly in my name and I really came to grips with my privilege and class background, the denial came apart," Schweser remembered. "I realized: I am literally the Man."

Some philanthropy experts argue that this kind of giving is important because it does not demand guaranteed success.

"Social change takes a long time," said Joe Voeller, a spokesman for the Ford Foundation, which has given Resource Generation three $100,000 grants since 2002. "Social justice philanthropy needs young donors who are not treating it as a passing fad but are committed to walking the walk."