It’s been 21 years since fashionable music power couple and philanthropic do-gooders Sting and Trudie Styler founded the Rainforest Fund. This thriving organization’s goal is to preserve, protect and restore areas of the world’s rainforests that are less-than-thriving. In addition to their many year-round events and efforts, the Rainforest Fund throws a pretty epic bash twice a year that more often than not features A-list guests and performers of the hosting couple. This year, they’re pulling no punches with the entertainment; Elton John, Sting, Lady Gaga and Dame Shirley Bassey (and undoubtedly a few surprise guests) are set to take the stage together at Carnegie Hall on May 21st, in celebration of the 21st birthday of charitable organization, which has raised more than $30 million for its efforts, which have expanded to cover 23 different countries. The bi-annual benefit event will also include a gala dinner and live auction following the concert. Of Lady Gaga and her co-stars, Trudie Styler said recently: “"She's such a great young woman…It’s a winning combination - we're going to have a riotous time up there. Sting, Elton and Gaga will play together, and the boys will be performing with Dame Shirley, doing a great rendition of 'Hey Big Spender.'" The big name line-up follows in a strong tradition of coming out with bravado to support the cause. Past performers include Billy Joel, James Taylor, Sting, Brian Wilson, Feist, Patti LaBelle, Smokey Robinson, Tom Jones, Lyle Lovett, Stevie Wonder, Bruce Stringsteen, Paul Simon, Whitney Houston, Lenny Kravitz, and Luciano Pavarotti, among many others. If you want to get in on the shindig, look for tickets to go on sale through the Carnegie Hall box office in early April.