Emmy Rossum

Photo: Chris Craymer

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Tux Redux #1: Take a Shine to Glittery Pants
Tired of the same old cocktail dress? Try a tux! Rossum, who plays sassy Fiona Gallagher on Showtime's Shameless, takes the classic men's staple and makes it hers for the holidays. "It's a softer, more contemporary version of the Katharine Hepburn look," she says. Here, that means sequined pants (Alice + Olivia by Stacey Bendet, $396 at Shopbop.com), a white button-down (New York & Company, $40), and a blazer with attached vest (Tory Burch, $495). "I love sparkle; I really do," says Rossum. "And I love big hair. I should be from Texas."

Earrings, Forevermark. Ring, Miriam Salat. Pin, Sophia 203, available at shoplatitude.com.

How to Wear It: Tips from O creative director Adam Glassman:

• Forget the old rules—you absolutely can wear pants to a black-tie event.

• Pair softer pieces with structured ones—palazzo pants with a fitted blazer, for instance. A loose top and bottom will just look sloppy.

• Balance masculine looks with feminine details: Try a soft blouse, bustier, or—if the buttons are high enough—nothing at all under a jacket. You don't want to look like you've borrowed your husband's tux.