Rachel Zoe builds a Halloween costume like she builds an outfit: chicly.

"Halloween is all about not trying too hard -- I like using what I have in my closet to build a character with a few key pieces," the fashion designer and celebrity stylist told us. "It's fun to be someone else for the night and play with hair and makeup."

Case in point: She rocked a Cher costume, complete with an oh-so-stylish fur vest and jewels, last weekend at Kate Hudson's swanky Halloween party. Hubby Rodger Berman went as Sonny Bono.

As for tonight, 42-year-old Zoe, who is expecting her second child, told us she plans to take her son Skyler, 2, trick-or-treating with friends and family.