Kate Beckinsale floated down the red carpet in a voluminous tulle gown by Marchesa.
Ashley Olsen looked all grown up as she posed in a dramatic white gown from her twin sister Mary-Kate's label with her boyfriend, Justin Bartha. We're loving her sleek bob!
Justin Timberlake sported a classic tux from his own William Rast line, while Jessica Biel, opted for a billowing Atelier Versace gown and sexy stilettos.
Jessica Alba sparkled in a bright blue, black, and green mini by Jason Wu.
Kate Hudson, Liv Tyler, and Kate Bosworth lit up the red carpet in gowns designed by Stella McCartney.
Blake Lively in Versace's Spring/Summer collection.
Can't wait to see what the fashionistas strut down the carpet in tonight.