She wore an edgy burgundy cocktail dress with a pleated skirt and black cord-laced straps by Versus by Versace for her first photo call, and a fancier, more feminine aqua-colored silk draped dress by Giambattista Valli later for the red-carpet premiere of "Moonrise Kingdom."
"This girl knows how to edit herself perfectly," says designer Rachel Roy, who is keeping tabs on the Cannes fashion show from New York.
Of the aqua gown, Roy says, "The transparency and draping is reminiscent of the Jacqueline Kennedy mint green moment, yet modern. ... Pure elegance."
Also on the red carpet, Eva Longoria chose a frilly Marchesa column gown in blush tulle with a dramatic ruffled skirt and train, and Jessica Chastain wore a light-pink, scoop-neck gown by Alexander McQueen. Eva Herzigova did pink, too — hers a Dolce & Gabbana.
Lana Del Rey attended in a black, scalloped, strapless Alberta Ferretti gown.
Some of the men captured the more relaxed vibe of the seaside resort: Bill Murray put on a plaid jacket, and Ewan McGregor paired his navy cotton suit by Marni with white lace-up shoes and a star-print tie.