In the three decades since Microsoft launched a program encouraging employees to give to charity, the software company’s workers have raised $1 billion.

Back in 1983, Microsoft started its Employee Giving Campaign, an initiative that donates $17 for every hour an employee volunteers and also matches every employee contribution to charity, dollar-for-dollar.

The company says 65 percent of employees have gotten involved, accounting for more than 35,000 participants, and Microsoft announced Thursday that the program has generated $1 billion for 31,000 nonprofits and community organizations around the world.

“The company and its employees have much to be proud of at this remarkable milestone and, I know, will continue to make a positive impact in the years ahead,” Microsoft Chairman Bill Gates said in a release.

To celebrate, Microsoft announced a $25,000 grant to the top four organizations that have received the most funding from Microsoft employees: United Way of King County, World Vision International, Seattle Children’s Hospital Foundation and the American National Red Cross.

But Gates isn’t just working on getting those toiling away at Microsoft to part with their money for worthy causes. As the richest person in the United States, he is continuing to urge other billionaires to donate significant chunks of their fortunes, too.

The Giving Pledge, launched two years ago by Warren Buffett and the Bill and Melinda Gates Foundation, asks billionaires to pledge half of their wealth. The campaign (which includes the likes of Facebook Founder Mark Zuckerberg and New York Mayor Michael Bloomberg) recruited 11 new billionaires just last month, bringing the total number of members to 92.

“This new group brings extensive business and philanthropic experience that will enrich the conversation about how to make philanthropy as impactful as possible,” Gates said in a statemement when the new members joined in September. “Their thoughtfulness and deep commitment to philanthropy are an inspiration to me, and I’m sure to many others as well."

Click through the slideshow below to see which other billionaires have pledged to give half of their fortunes away.

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  • George Lucas

    Hollywood director George Lucas is passionate about education. He has worked to foster positive growth in the education sector through, <a href="http://www.edutopia.org/" target="_hplink">Edutopia</a>, the George Lucas Education Foundation. Lucas plans to donate the majority of his fortune to this end.

  • Paul G. Allen

    Microsoft co-founder Paul Allen has supported his namesake, the <a href="http://www.pgafoundations.com/" target="_hplink">Paul G. Allen Family Foundation</a>, for more than 20 years, as well as helped advance nonprofit scientific research through the Allen Institute for Brain Science. Allen has already given hundreds of millions of dollars to charity through his foundation, and has expressed his commitment to give the <a href="http://www.huffingtonpost.com/2010/07/15/paul-allens-charity-promi_n_648142.html" target="_hplink">majority of his fortune</a> after his death.

  • David Rockefeller

    The Rockefeller family has historically been involved in philanthropic efforts supporting University of Chicago, <a href="http://www.rockefeller.edu/" target="_hplink">The Rockefeller University</a>, the Museum of Modern Art, and the <a href="http://www.rbf.org/" target="_hplink">Rockefeller Brothers Fund</a>. David Rockfeller, the current heir, has pledged the majority of his wealth to charity.

  • Michael Bloomberg

    Mayor of New York City Michael R. Bloomberg plans to give away the majority of his wealth during his lifetime, explaining that it is a better way to ensure a <a href="http://givingpledge.org/#michael+r.+_bloomberg" target="_hplink">better future for his children</a> than leaving them to inherit his fortune. According to Bloomberg, his <a href="http://www.mikebloomberg.com/index.cfm?objectid=B96D19BD-C29C-7CA2-F72C5EDC3BEDFA6A" target="_hplink">foundation</a> is currently working to find ways to prevent early deaths caused by tobacco use and traffic accidents.

  • Barron Hilton

    Barron Hilton (left) plans to immediately pledge over $1 billion to the <a href="http://www.hiltonfoundation.org/" target="_hplink">Conrad N. Hilton Foundation</a>, which provides funds for nonprofits addressing a variety of issues, including homelessness, access to clean water and disaster relief. Hilton also plans to follow an example set for him by his father, donating the remaining 97 percent of his wealth in the future.

  • Jon and Karen Huntsman

    After losing his mother to cancer, businessman Jon Huntsman felt called to found the <a href="http://www.hci.utah.edu/" target="_hplink">Huntsman Cancer Institute</a> and use his fortune to find a cure for cancer. Huntsman plans to leave his entire estate to his foundation and other cancer-related charities.

  • Ted Turner

    In 1998, media mogul Ted Turner donated $1 billion to start the <a href="http://www.unfoundation.org/about-unf/" target="_hplink">United Nations Foundation</a>. Turner plans to continue giving, saying that his fortune should be almost completely distributed to charity at the time of his death.

  • Alfred Mann

    In 1985, businessman Alfred Mann founded the <a href="http://www.aemf.org/" target="_hplink">Alfred Mann Foundation</a> to fund scientific research in the field of medicine. Mann has joined the ranks of the 'Giving Pledge,' planning to commit 90 percent of his estate to his foundation and other causes.

  • Eli and Edythe Broad

    Billionaire businessman and real estate mogul Eli Broad and his wife, Edythe, have pledged to give away 75 percent of their fortune within their lifetimes. The <a href="http://www.broadfoundation.org/" target="_hplink">Broad Foundation</a> supports arts organizations, funds advancements in medical science and advocates for education reform.

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