Bill and Melinda Gates and Warren Buffett are launching a drive to persuade billionaires to give away the majority of their fortunes.

They are asking fellow billionaires to sign a "Giving Pledge," making a public statement to donate most of their wealth to philanthropic causes of their choice.

The pledge isn't legally binding, but they hope the effort will generate more money to address important social problems and set a standard that becomes the norm, former Gates Foundation CEO Patty Stonesifer, who is an adviser to the Gateses, said in an interview today.

SETH WENIG/ASSOCIATED PRESS

Investor Warren Buffett, who is ranked as the third richest person in the world, is donating most of his wealth to the Gates Foundation.

Buffett, who pledged to give away more than 99 percent of his $47 billion fortune, was the main driver of the initiative, which has the support of a couple dozen billionaires, Stonesifer said. Buffett was inspired not by the rich but by the generosity of ordinary people who sacrifice more to contribute hard earned dollars to churches, schools and other organizations.

The idea came out of a series of private dinners the Gateses and Buffett held in New York and the San Francisco Bay Area over the past year. They will invite people who take the pledge to meet at an annual event to share ideas.

The potential for philanthropy is huge -- the United States alone has at least 400 billionaires with a net worth Forbes estimates at $1.2 trillion. If those billionaires gave the minimum pledge of half of their fortunes to charity, that would triple the current amount of charitable giving in the U.S.

"That could be transformational," said Phil Buchanan, president of the Center for Effective Philanthropy. "It could have a dramatic effect on some of the toughest social challenges that we face. But people have to do it first."

The Giving Pledge does not involve pooling money or supporting particular causes. But philanthropic efforts have the most impact when different non-profits and foundations unite around the same cause, often bringing in support from businesses and policymakers, Buchanan said.

"There are so many pressing human needs and the temptation is so great to want to address all of them," Buchanan said. "There's going to need to be collaboration among philanthropists to move the needle in significant ways."

Four couples have already signed on to the pledge, Stonesifer said. They are Eli and Edythe Broad, John and Ann Doerr, Gerry and Marguerite Lenfest and John and Tashia Morgridge.

In his pledge letter today, Buffett describes how having too much wealth is a burden.

"Too often, a vast collection of possessions ends up possessing its owner," he wrote.
"Were we to use more than 1% of my claim checks on ourselves, neither our happiness nor our well-being would be enhanced."

How are some of the country's billionaires reacting to the plan? Forbes has an interesting smattering of answers from Donald Trump and others here.

Washington state is home to six billionaires: Bill Gates, Microsoft Chief Executive Steve Ballmer, Microsoft co-founder Paul Allen, Amazon.com Chief Executive Jeffrey Bezos, wireless entrepreneur Craig McCaw and Oakley sun glasses creator James Jannard, who lists his residence in the San Juan Islands.

"This is an exciting idea and sets a new standard for charitable giving," said Susan Coliton, vice president of the Paul G. Allen Family Foundation. Allen was out of the country and unavailable for comment. He has been ranked among the top philanthropists for years, Coliton said, adding "I am sure he will be interested in learning more about this challenge from Warren Buffett and Bill and Melinda Gates."

Ballmer said in a recent interview that he and his wife preferred to keep their philanthropy private and anonymous. McCaw declined to comment. Bezos and Jannard could not be reached Wednesday.

Leaders of the pledge will have their work cut out for them. It turns out the richest Americans are not all that generous.

"We agree with Andrew Carnegie's wisdom that 'The man who dies rich, dies disgraced,' and we also believe 'he who gives while he lives also knows where it goes,'" the Broads said today in a statement along with their pledge to give 75 percent of their wealth to charity.

Giving may be rewarding, but it's not that easy, they said.

"Philanthropy is much harder than running two Fortune 500 companies."