Stars were dressed to impress as they hit the party circuit on Thursday night. Emmy Rossum mastered the look of love, attending The W Hotel opening in Washington, DC. The actress, who dressed up in a formal, white gown Wednesday night for the American Ballet Theater’s 2009 Fall Gala, showed off her hot bod in this black mini dress.

PHOTOS: See Emmy Rossum, Naomi Watts, Alicia Silverstone, Paris Hilton, Bai Ling, Lisa Rinna, And Kristin Davis Dressed In Their Best!

Who got issued a Fashion Police citation?  Read on to find out!

PHOTOS: See Emmy In Her Gown!