Most clients who come to Neilson—half celebrities, half less conspicuous wealthy donors—have a clear idea of what issue they want to tackle. About a quarter arrive without a cause, just with the urge to do something. The staff's work begins with questions that help them find options that play best to a client's image and audience. What are your core values? What injustices make you angriest? How much time do you have to work on this? In other words: What matters to you? Then Neilson and his team select a suitable issue and offer advice on how best to address it.

"Certain brands are incompatible," Neilson explains. He is back in Santa Monica, dressed in dark jeans and a crisp burgundy gingham shirt. When the fashion designer Tory Burch wanted to get into childhood-hunger issues, Neilson helped her realize that her entrepreneurial skills were better-suited to microfinance. Soundgarden's frontman, Chris Cornell, wants to get involved in children's issues. "You can slice and dice that 40 ways," Neilson says. "Children with disabilities, disease, physical or mental handicaps. But it's got to be in a way his fans can relate to. He's a hard-rock guy. He's not gonna be all like, 'Please come save the children.' "

When Neilson first met Kutcher and Moore a year ago, they knew they wanted to fight sex trafficking. Kutcher had a philanthropic track record—using Twitter to rally a million followers and raise money for malaria nets in Africa—and he and Moore had seen a 60 Minutes segment on child sex workers in Cambodia. But they were unfocused in their approach. "They hadn't created a foundation, didn't have a business plan, didn't have a strategy," says Neilson. The GPG team, with Kutcher and Moore on board, agreed that, given Kutcher's domestic popularity, they should go after the demand side in the U.S. Neilson put four people on the account, and the group developed a 140-point plan of attack ("I don't want to give away too much of the secret sauce," Neilson says with a wide smile). He introduced the couple to State Department experts. He brought them to the California-Mexico border, where they met with a 13-year-old trafficked rape victim. He brokered a deal with the Department of Homeland Security that cast them in training videos teaching people how to spot trafficked sex slaves. ("Cops especially respect Demi because of her law-enforcement roles," says Neilson, referring to A Few Good Men and G.I. Jane.) The next step was putting a White House stamp of approval on the foundation. In May, Neilson set up a press conference for Moore on Capitol Hill. She brought along three female sex slaves to tell their stories in a meeting with a senior White House adviser. The media paid attention. Days later the couple was appearing in Parade and on CNN.

There is, in all of this, an undeniable element of image scrubbing. It used to be that celebrities donated their money, and some face time, to established charities like the United Way. Then came Band Aid and USA for Africa-style benefits, in which stars pooled their influence for a cause. But in its annual look at the biggest celebrity givers this year, Forbes noted that around a quarter of the stars on the list now have their own foundations, allowing for maximum image control and exposure. "It's become somewhat of a status symbol to have your own charity these days," says Marc Pollick, founder of the Giving Back Fund, which helps pro athletes like Yao Ming and Ben Roethlisberger develop their own philanthropic brands.

A personal charity is also helpful, as in the case of Kutcher and Moore, in deflecting negative press. The foundation's first media blitz appeared a month ahead of the critically panned Killers, starring Kutcher (at the premiere, he held up a Real Men Don't Buy Girls poster, almost like a shield). And although it wasn't planned this way, the Real Men campaign gave the press something to ponder other than Kutcher's alleged infidelity, reported earlier that week in Star magazine (Kutcher declined to be interviewed for this story).

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Neilson is sitting poolside at the Viceroy hotel in Santa Monica. It's a sunny Thursday after work, and he is having a beer as he tends to his BlackBerry.

"People recognize that if a celebrity is serious about their philanthropy, their image will improve," he says. "I welcome that. People say, 'All this philanthropy Bono does just results in him being in the headlines.' I just say, 'You're goddamn right. And I'm glad.' The more rewarded an artist is for doing philanthropy, the more other people are going to want to do it."