CBS Evening News anchor Katie Couric spoke with two of the billionaires about The American Spirit Of Giving.
Ninety-one years after his death, industrial giant Andrew Carnegie's praises are still being sung. For him, philanthropy was a religion - it even has a gospel according to Carnegie.
"The man who dies leaving behind many millions of available wealth will pass away unwept, unhonored, and unsung," he said in 1914.
Warren Buffett is a believer. So is Bill Gates, and together they are spreading the message that the richest people should give most of their money away while they're still alive.
AOL co-founder Steve Case, and Wall Street tycoon Ted Forstmann are two of the latest converts to sign "The Giving Pledge."
Even though Forstmann already gives away lots of what he has, he said he signed the pledge because Mike Bloomberg asked him to. "He convinced me that adding your name to this would be helpful. Maybe other people would do it as well," Forstmann said.
@katiecouric: The Giving Pledge
Case said it was a "relatively easy" decision for him. "You have the opportunity to have great resources there's a responsibility to use them in a constructive way."
Case and his wife Jean established the Case Foundationin 1997. Together they've supported efforts like a Twitter campaign to stop malaria, and an online giving challenge which raised more than $2 million last year for 8,000 charities.
Forstmann co-founded the Children's Scholarship Fund, which has given nearly half a billion dollars in tuition money to more than 100,000 needy children.
The charity has changed lives, but Forstmann said the boys he adopted changed his.
"My two kids were street orphans in South Africa that I met through Nelson Mandela," he said. "Anything where children have a bad deal is what gets me."
The Giving Pledge is the ultimate rich list that's enriching the lives of millions. Their philanthropy comes at a critical time for charities in this country. The recession has taken its toll on donations. Last year Americans gave $303 billion, but that was down nearly four percent from 2008.
"To the extent you can help out if you don't you're a jerk," Forstmann said. "I don't think what Steve and I are doing is great at all. I think if you don't do it, you're a jerk."
Case added, "we have big problems in this world and we have to kind of join together to try to solve them. And this is one way to do it."