Justin Bieber, Kim Kardashian among those who sign the 'Hollywood Pledge'

Hollywood stars like Justin Bieber and Kim Kardashian are hoping to cash in on their fame and 'social capital' and draw attention to charities by making the 'Hollywood Pledge.'

American reality show star Kim Kardashian appears at a charity fashion show in Monaco May 27. She is one of scores of celebrities who have signed a 'Hollywood Pledge,' fashioned after the 'Giving Pledge' started by billionaires Bill Gates and Warren Buffett in which they promise to give away to charity the majority of their fortunes.

VINCENT DAMOURETTE/EFE/Newscom

June 3, 2011

Hollywood celebrities have long taken part in charity events, an opportunity to be seen in a favorable light. But now some of them are making a more formal pledge to do charitable work.

They're taking their cue from a group of generous billionaires, headed by Bill Gates and Warren Buffett, who have promised to give away the majority of their fortunes to worthy causes in a Giving Pledge.

As with the billionaire group, which now numbers nearly 70, the "Hollywood Pledge" allows each person to customize his or her own pledge. The giving may be in the form of donations or charitable work, such as visiting a children's hospital or hosting a fundraiser. Each celebrity can list the causes he or she is supporting, and can invite fans to get involved through volunteering or making a donation.

Among the well-known actors, musicians, athletes, and other personalities who have already taken the pledge are Justin Bieber, Laurence Fishburne, Richard Gere, Jewel, Dwight Howard, Hugh Jackman, Kim Kardashian, Ricky Martin, Kelly Osbourne, Rachel Zoe, Jordin Sparks, Adrian Peterson, and Denzel Washington.

The project is sponsored by The Give Back Hollywood Foundation, formed to help celebrities get more involved in charitable work, especially in the areas of children, health care, and disaster relief.

“The Hollywood Pledge, inspired by the ‘Giving Pledge,’ is a natural evolution of this effort and intended to drive the adoption of charity causes by the leading figures in entertainment, which in turn can become an incredible motivator for fans worldwide to embrace the same commitment,” said the foundation's founder and president, Todd Krim, in a press release.

“A celebrity’s capital is in form of their social capital, not cash. If Justin Bieber were to tweet something to 120 million people, that may be even more effective than a $100,000 donation in some ways,” Krim told MSNBC.com in an interview. “Most billionaires don’t have the name recognition or star power that celebrities do.”

The webzine "Look to the Stars" follows the charitable work of the rich and famous. It says it's currently tracking 2,574 celebrities involved in 1,702 charities.