When Reese Witherspoon [1] decided to host an event for Stand Up to Cancer, she packed her guest list with a who's who of Hollywood. And while the stars were out for a good cause, they brought their beauty A-game. See all the looks from the night here.

Reese Witherspoon

Jessica Alba

Diane Kruger

Selena Gomez

Anne Hathaway

Heidi Klum

Gwyneth Paltrow

Drew Barrymore

Christina Aguilera

Emma Roberts

Lily Collins

Anna Kendrick