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From sidekick to superstar, Richie perfected casual glam (left, in Miss Sixty jeans and a Curve camisole) and red-carpet radiance (in vintage Azzaro, center, and Moschino Couture). "She's had a mega year, stylewise," says PEOPLE fashion director Susan Kaufman. "She favors vintage, and sometimes she creates a '70s character out of her look. Girls everywhere copy her."
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After morphing from curvy redhead to skinny blonde, Lohan found her groove as a couture-clad brunette with a rock 'n' roll edge. Her signature: flat-heeled boots (left) and very little black dresses by Chanel (right). "Her look has gotten edgier, with her platforms and short dresses," says Kaufman. "It's more of a New York style than an L.A. style."
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Dawson wore a frumpy gown to 2004's Alexander premiere (left). This year, the Rent star flattered her curves in frocks by Michael Kors (center) and Gucci. "She's gone from being sort of bedraggled to looking sophisticated," says Kaufman. "Her natural tendency was to be more street, funky and casual. Now she's accepting that she's a beautiful woman and dressing accordingly."
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Miller's favorite things include her Burberry boots (left and center) and mod Balenciaga jacket (left). "She loves certain accessories, and doesn't feel the need to change them every day," says Kaufman. On the red carpet (in John Galliano for Dior), "she wears couture, but her hair's a little messy – she's never going to be that perfect, polished glamor girl. She never looks manufactured."
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Last year, Duff, then 17, hadn't left her teen-queen roots behind (left). Today, the singer-actress (in Zac Posen, center, and Alessandro dell'Acqua) looks every inch the young mogul she is. "She's gone from being overaccessorized to simplifying and letting her own personality stand out, rather than layering herself in thousands of necklaces and bangles," says Kaufman.
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The Match Point star looks polished whether she's casual (left) or dressy (in Marchesa, center, and Moschino). "She has a total va-va-voom figure, and she's really not a very trendy dresser," says Kaufman. "She can do that old Hollywood thing – showing off her curves, putting on the full hair and makeup. She's going to be one of the perennial best-dressed."
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"Designers love to dress her. Because she used to be a model, she's beautiful and she makes clothes look great," says Kaufman of the Get Rich or Die Tryin' star, who looked runway-ready in (from left) a tuxedo-style jacket and jeans, vibrant Donna Karan and a Ralph Lauren gown paired with a leather belt. "She's a little bit of a hippie chick – her look is always easy, never contrived."
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The former child star still dressed girlishly in '04 (left). But this year, she released the album This Woman – and dressed the part (in Moschino, center, and J. Mendel). "One of the most remarkable makeovers of the year," says Kaufman. "With her hair slicked back, subdued makeup and a very elegant gown, she could almost be a Grace Kelly."
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Jessica's little sis is all grown up, having traded last year's '80's-inspired getups (left) for streamlined jeans-and-blazer combos (center) and designers such as Giambatista Valli. "She's showing off her body, wearing heels," says Kaufman of Ashlee's improved look. "She's just becoming more comfortable in her own skin."
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"You could put Charlize in a potato sack and she'd look great," Kaufman says. But luckily, the Aeon Flux star prefers designers such as (from left) Dior Haute Couture, Gucci and Ralph Lauren. "She's tall, she's thin, she's a former model, she has impeccable taste. Very few actresses can pull off couture the way she can."