Mary-Kate Olsen attends the New York City premiere of "Holy Rollers" clad in a leopard-print blouse and black harem pants and toting a fringed bag.

Style tip: Granted, slouchy pants are not for the unadventurous. But take a cue from Olsen and you'll rock the harem pants trend with pizzazz -- pick a tailored pair in slimming black and match with a sexy top -- think a fitted camisole or an animal-print top.

Mary-Kate Olsen brings her penchant for all things vintage to the 2009 Costume Institute Gala, where she shines in this Victorian-inspired sequined-and-lacy tiered gown from Christian Lacroix Fall 2007 Couture.

See more star styles at the 2009 Costume Institute Gala.

Mary-Kate Olsen captures the strong-shouldered silhouette of the Eighties in this shoulder-padded Balmain LBD. In a nod to the decade of excess where more is more, the actress readily piles on those big blings.

Even oversized granny cardigans look uber chic when you're an Olsen twin. The pair demo two stylish ways to work the oversized trend at the signing of their new book "Influence" at Border's bookstore in California.

Mary-Kate (right) converts her baggy button-up shirt into a shirt-dress by wearing it on its own, accessorized with a bold-hued belt and edgy open-toed boots. Ashley goes for layering and teams her knee-length cardigan coat with a simple top and mini-skirt. As a finishing touch, on each of the twins' finger is, yes, an oversized ring.