Cameron Diaz, Chris RockJohns PKI/Splash News

InStyle‘s May cover girl Cameron Diaz and Chris Rock walked the red carpet at a New York screening of their new comedy, What to Expect When You’re Expecting. The film about five couples whose lives are turned upside-down by parenthood, out May 18th, explores a theme that Diaz is familiar with: getting comfortable with life’s surprises. “I’ve never said I don’t want children—I just haven’t had children yet, ” she told us in our May issue. “I don’t know what’s going to happen in my life!” See more stars at last night’s hottest parties in the gallery.