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“I just think it’s so fun when you do fashion with a good cause,” Emma Roberts told InStyle.com before joining Emily Mortimer, Rachel Bilson, and more for Chanel’s benefit supporting the Natural Resources Defense Council (NRDC) this weekend. Held at the Los Angeles home of art dealer Larry Gagosian, formerly owned by acting legend Gary Cooper, the event raised awareness and funds to support the organization’s mission of saving the earth’s resources and environment. While Bilson wandered around admiring Gagosian personal art collection, most guests gathered pool-side to sip on Champagne and snack on hors d’oeuvres in the balmy night. As the sun set over the magnificent garden, Patti Smith and Karen O from the Yeah Yeah Yeah’s performed “Because the Night” and “Perfect Day.” Bella Heathcote, who admitted that she squealed when she heard Smith was going to perform, really got into the music, dancing by the side of the stage. After the performance, guests took their seats at long tables covered in white linens under the starry sky to enjoy a vegetarian meal created by Travis Lett of Gjelina. Click to see more.

— Carita Rizzo