Costume Institute Gala: See the Dresses!

J.Lo, Renée and a pregnant Naomi Watts wow the NYC crowd. By Andrea DeSimone

ASHLEY OLSEN

There's no confusing the sisters tonight! The other Olsen looks sleek and chic in a never-been worn John Galanos belted white sheath with Fred Leighton jewels and Lily et Cie clutch.