Cameron Diaz, Russell SimmonsSipa USA

May cover girl Cameron Diaz and Russell Simmons spoke up for science at the fourth annual Greenhouse Project Benefit, hosted by New York Sun Works at the Standard Hotel in New York City. “Uplifting one student at a time through science education. Great work,” Tweeted Simmons en route to the event. The yearly gathering helps the organization raise money to build science labs on the roofs of public schools. Click through to see more stars at last night’s biggest parties.