Two of the world's richest men are calling on other billionaires to give large portions of their fortune to charity.
Microsoft's Bill Gates and billionaire investor Warren Buffett want the country's rich to give at least half their wealth to charity during their lifetime or through their wills.
In 2006, Buffett decided to give 99 percent of roughly $46 billion fortune to charity.
"It's a moral obligation and it's a serious pledge," Buffett said. "But it's not a legal pledge. It's a moral pledge"
"And we want to get the people who do this together. We think they can share ideas, learn from each other, encourage others," Gates added. "And so we're kicking this idea off and going to invite lots to join in."
Gates and Buffett estimate "The Giving Pledge" could raise $600 billion in charitable giving.
The pair said they were inspired by the millions of Americans who give generously, even when it means sacrificing something for themselves.