Hot Trend: Retro Fashion

With her blonde hairstyle and va-va-voom clothes, Christina Aguilera is "channeling Marilyn Monroe," says PEOPLE style director Susan Kaufman. From her "sweater girl from the '50s look" (right) to her "slip dress with satin evening coat" (left), Aguilera relives the style hallmarks of that decade.

"This is not a guy who wants to blend in," says Kaufman of Oscar nominee Johnny Depp. His brightly colored "zoot suit" and spats (left) make him look like a jazz cat from the era, while his casual streetwear (right) is a '40s man-about-town look. "Johnny Depp likes to march to the beat of his own drum and that translates to his style."

Jennifer Lopez "mixes up elements of the '70s" with her floppy hat and platform boots (left), says Kaufman. And in her fringed poncho from her Sweetface fashion line (right) and knee-length boots, "she's very much like Cher from the early '70s. It's a hippie moment."

Usher loves looking dapper, and what better decade to draw inspiration from than the 1920s? The singer sports a double-breasted waistcoat and two-toned shoes along with some modern bling at the Grammys (left) while his 26th-birthday party suit (right) is a "very early Fred Astaire look," says Kaufman. "The top hat, the white gloves, the cane, the longer jacket – it's that kind of free-swinging, '20s party mode."

Both Mary-Kate Olsen (left) and Scarlett Johansson (right) have a "very '90s grunge feeling of layering, looking like you're thrown together," says Kaufman. "It's sort of like, 'That sweater's lying on the chair – I'll throw that on top of this.' The look is supposed to be, 'I didn't plan this. These are clothes I just had sitting around.' "

Oscar winner Cate Blanchett's Valentino gown (left) is reminiscent of 1940s movie star Rita Hayworth, says Kaufman. Meanwhile, the silhouette of her Stefano Pilati for Yves Saint Laurent suit (right) is also a throwback to the silver-screen era. "The shoulders got a little wider, the waists got really narrow and the skirts got very streamlined," she says of the decade.

"The '80s were so much about being over the top. How big can the hair get? How tight can the jeans get?" says Kaufman. Beyoncé captures that look at the launch event of her True Star perfume (left). And her pastel gown, giant necklace and colorful makeup (right) "also have an '80s feeling."

British actress (and Jude Law's fiancée) Sienna Miller is influenced by 1960s style (left) with her "bohemian touches, like taking her big studded belt and wrapping it around as a dress top, and the cuffed-over hippie boots," says Kaufman. And her chic embroidered shearling coat (right) "was such a quintessential late '60s item."

Natalie Portman "has said the reason she loves the 1920s is that when she's dressing for the red carpet, she likes to be comfortable. These looks aren't body conscious," says Kaufman. Though her Chloe gown (right) is a little longer than most dresses of the time, its drop waist recalls the era. Meanwhile, her short bob with its finger waves and her lacy dress (left) gives another taste of the Roaring '20s.

Just call him Superfly. Kravitz draws his wardrobe inspiration from the groovy early 1970s. "He's very David Soul from Starsky amp Hutch with the leather jacket over the suit and boots and the aviator sunglasses," says Kaufman of Kravitz at a New York City event (left). Onstage (right), he takes another route back in time to the Me Decade with his studded denim vest, bell bottoms and knit cap.

Gwen Stefani (who played '30s screen queen Jean Harlow in The Aviator) relives the decade with her bias-cut Atelier Versace gown and shiny tresses (left). "The platinum blonde really is the iconic '30s movie-star look," says Kaufman. And her Dior Greek goddess-like draped dress (right) is also a nod to the past. "John Galliano for Dior is completely inspired by the gowns of that era."