Olivia Wilde - Ashley Greene
Credit: Todd Williamson/WireImage

Olivia Wilde and Ashley Greene were among the socially-conscious stars who posed pretty at the 10th Annual Chrysalis Butterfly Ball in Los Angeles. "I love these events because everyone here tonight is gathered for the right reasons," said Wilde (in Yigal Azrouel) of the event, which raised funds to help the city's homeless population. "Hollywood may get a bad rap, but it’s a very generous community and I’m proud to be a part of it." Click through the gallery to see Cameron Diaz, Ashley Tisdale, Christie Brinkley and more stars at this weekend's hottest parties!