Nicole Richie and Kate Bosworth hosted a bash in LA last night celebrating their pal Derek Blasberg's new book, Classy: Exceptional Advice for the Extremely Modern Lady. Derek's currently in the midst of a cross-country book tour that included a stop San Francisco, where he shared five fashion no-nos with Fab. Nicole was with Joel and their daughter, Harlow, earlier in the day, but her date for the evening was her soon-to-be brother-in-law Benji. Nicky Hilton, though, was the one subjected to Nicole's sense of humor while they posed for a photo. The evening was all about starlets, fashion, and Derek, but the party also interestingly brought out the apparently reconciled couple Balthazar and Rosetta Getty.

To see more from Derek's party just


Images include: Kate Bosworth, Nicole Richie, Mischa Barton, Nicky Hilton, Benji Madden, Patricia Arquette, Charlotte Ronson, Balthazar Getty, Brent Bolthouse, Margherita Missoni, Derek Blasberg, Liz Goldwyn, Dasha Zhukova, Rosetta Getty