Dozens of the world’s top movie, television and music stars showed off their green cred on Saturday night at a Hollywood-style fundraiser honoring the Natural Resource Defense Council‘s 20 years in Southern California.

The event at Beverly Hills’ Regent Beverly Wilshire Hotel was a who’s who of Hollywood environmentalists, including actors Leonardo DiCaprio and Robert Redford, and Laurie David, a global warming activist and producer of the Al Gore movie “An Inconvenient Truth.” All three are trustees of the NRDC’s Southern California office. In 2003, the group even dedicated its new building to Redford.

It’s no secret that the environment and climate change is a hot cause in Hollywood, and it’s hard to imagine another social issue drawing as much star power to one event. The party also raised a hefty $2 million.

“Mad Men” star Jon Hamm and designer Tom Ford also attended the party, which was hosted by “Seinfeld” star Julia Louis-Dreyfus and included a musical performance by Grammy-winning rockers Maroon 5. Actress Rosanna Arquette deejayed the after party.

On stage, Redford recalled why he joined the NRDC in the 1970′s, saying it was “because they had the power to sue.”