Warren Buffett and Bill Gates called Wednesday on their billionaire peers to give away half of their wealth.

The pronouncement by Messrs. Buffett and Gates stems from a series of dinners the two men held over the past year to discuss the effects of the recession on philanthropy with some of the nation’s richest people, including New York Mayor Michael Bloomberg, investor Ronald O. Perelman and David Rockefeller, his family’s patriarch.

The result of the dinners is an invitation, called the Giving Pledge, which asks the nation’s billionaires to publicly commit to give at least half of their wealth to philanthropic and charitable groups within their lifetimes or after their deaths.

The effort casts a spotlight on a highly private decision, and inserts Messrs. Buffett and Gates into the process. While several attendees of the dinners have made the pledge, many of the nation’s wealthiest already had decided to disburse the bulk of their wealth to charitable causes.

The goal is to help create an expectation in society that the rich should give away their wealth and to create a peer group of wealthy people that can offer advice on philanthropy, said Melinda Gates, Mr. Gates’s wife and co-chair of the Bill & Melinda […]