1. Warren Buffett

Berkshire Hathaway CEO

2003-07 Given or Pledged: $40,650 million
Favored Causes: Health, education, humanitarian causes
Estimated Lifetime Giving*: $40,780 million
Net Worth**: $52,000 million
Giving as a Percentage of Net Worth: 78%

Buffett's $31 billion commitment to the Bill & Melinda Gates Foundation, announced in June, 2006, resonates throughout the philanthropic community, inspiring other givers with a new model of philanthropy. The giving is aimed at funding education and global health initiatives. Buffett, the world's second richest man, also earmarked billions for the Susan Thompson Buffett Foundation, the Howard G. Buffett Foundation, and the NoVo Foundation—independent family foundations that support causes including reproductive health and worldwide conservation.

*Based on public records and interviews with donors
**Based on the Forbes 400 list and donor information
Data: BusinessWeek, GuideStar, The Chronicle of Philanthropy, The Center on Philanthropy at Indiana University