Fashion Looks of the Week By InStyle Editors InStyle Editors Facebook Instagram Twitter Our editors and writers comprise decades of expertise across the beauty, fashion, lifestyle and wellness spaces in print and digital. We prioritize journalistic integrity, factual accuracy, and also having fun with every story we share. InStyle's editorial guidelines Updated on December 6, 2013 @ 01:15PM Pin Share Tweet Email Trending Videos Photo: Lisa Maree Williams/Getty Looks of the Week 01 of 22 Kate Middleton Anthony Harvey/Getty WHAT SHE WORE At the royal premiere of Mandela: Long Walk to Freedom, the Duchess slinked onto the red carpet in an ivory Roland Mouret column accented by a diamond necklace and black accessories. 02 of 22 Naomie Harris Jon Furniss/Invision/AP WHAT SHE WORE Harris struck the perfect note at the Mandela: Long Walk to Freedom premiere, walking the red carpet in a black strapless Alexander McQueen gown with gold-embroidered peplum detailing. Her only accessories were a pair of statement danglers and a ring. 03 of 22 Emmy Rossum Jim Smeal/BEImages WHAT SHE WORE At the August: Osage County screening, Rossum went the ladylike approach with a navy silk faille sequin-and-floral embroidered Oscar de la Renta A-line dress, styling it with geometric earrings, an embellished clutch and white Rupert Sanderson pumps. 04 of 22 Elizabeth Banks Jerod Harris/Getty WHAT SHE WORE Banks got in the holiday spirit at Legoland's tree lighting ceremony in a mixed-print flared Preen dress that she topped with a J Brand leather moto jacket, Jacob amp Co. jewelry and black ankle boots. 05 of 22 Gabrielle Union Michael Stewart/Getty WHAT SHE WORE At the Alvin Ailey Dance Theater's benefit gala, Gabrielle Union showed up in a strapless styled Prada gown in a rich shade of emerald green. A diamond wreath at her neck and black T-strap heels completed her look. 06 of 22 Sandra Bullock Masatoshi Okauchi/Rex/REX USA WHAT SHE WORE Bullock premiered Gravity in Tokyo in a strapless blue fit-and-flared Carolina Herrera dress with a floral-embroidered sheer hem, pairing it Martin Katz jewelry and black peep-toes. 07 of 22 Jessica Biel Jeffrey Mayer/WireImage WHAT SHE WORE Biel proved that the cropped trend is here to stay, wearing a black midriff-baring Giambattista Valli top and a black lace skirt. For added drama, she topped off her look with a leather jacket, a sparkly bracelet and black lace Bionda Castana pumps. 08 of 22 Amanda Seyfried Lee Young-ho/Sipa USA WHAT SHE WORE As the face of beauty brand Cle de Peau, Seyfried fulfilled her spokeswoman duties in South Korea in a graphic red-and-black A-line dress, complementing the two-toned color palette with a bold red lip and black pumps. 09 of 22 Keira Knightley David Fisher/Rex/REX USA WHAT SHE WORE At the 2013 SeriousFun London Gala, Keira Knightley styled her pretty tulle long-sleeve Chanel Couture wedding dress for the red carpet with gold strappy Jimmy Choo heels. 10 of 22 Angie Harmon Nancy Kaszerman/ZUMAPRESS.com WHAT SHE WORE At the Ninth Annual UNICEF Snowflake Ball, Harmon stunned in a strapless black-and-white ruffled Angel Sanchez gown, with Lorraine Schwartz jewels. 11 of 22 Lea Michele Fernanda Calfat/Getty WHAT SHE WORE Michele stole the spotlight at the L'Oreal Paris Women of Worth 2013 event in a red Dolce amp Gabbana dress embellished with Swarovski crystals, pairing it with classic Christian Louboutin pumps. 12 of 22 Amy Adams Kevin Winter/Getty WHAT SHE WORE Adams struck a pose at the American Hustle premiere in a black-and-white David Koma pencil dress with a sheer hem, accenting the dress with Neil Lane diamond jewelry and embellished black Christian Louboutin pumps. 13 of 22 Olivia Palermo Leandro Justen/BFANYC.com/BFAnyc/Sipa USA WHAT SHE WORE Palermo nailed the menswear trend, topping off her all-black ensemble with an optic-white tuxedo vest. But it was her accessories that shone bright: A stack of bangles, a bejeweled brooch, a Stuart Weitzman clutch embellished with jade gems, and snakeskin pumps. 14 of 22 Allison Williams Cindy Ord/Getty WHAT SHE WORE At the 2013 Autism Ball Allison Williams worked the blue carpet in a frothy black Oscar de la Renta creation, with a lace bodice and tiers of tulle for the skirt. Delicate drop earrings, a black clutch and bold red lip completed her look. 15 of 22 Lupita Nyong'o Kristina Bumphrey/Startraksphoto.com WHAT SHE WORE Nyong'o went in a girly direction at the Gotham Independent Film Awards, wearing a white strapless bow-adorned Lanvin tea-length dress with red Lanvin pumps. 16 of 22 Shailene Woodley Monica Schipper/Getty WHAT SHE WORE Woodley attended the 23rd Annual Gotham Independent Film Awards in white-and-black Calvin Klein Collection halter dress, simply styling it with nothing except for black ankle-strap heels. 17 of 22 Kate Middleton Mark Cuthbert/UK Press via Getty WHAT SHE WORE At the SportsBall, Duchess of Cambridge styled a black lace knee-length Temperley London dress with a bright red Alexander McQueen clutch and black Jimmy Choo pumps. 18 of 22 Marion Cotillard Dominique Charriau/Getty WHAT SHE WORE At the 13th Marrakech International Film Festival in Morocco, Cotillard attended the premiere of A Thousand Times Good Night in a tea-length Christian Dior dress with playful candy-colored stripes, pairing it with delicate ankle-strap Dior stilettos. 19 of 22 Alicia Keys Norman Ko / Splash News WHAT SHE WORE Keys lit up the 27th Annual ARIA Awards 2013 in a sunny Stella McCartney gown, complete with a gold belt and a chunky gold chain necklace. 20 of 22 Gwen Stefani EROTEME.CO.UK/BAUER-GRIFFIN.COM WHAT SHE WORE Who knew dog-walking could be so chic? Stefani wore cherry-red long-sleeve dress (to match her signature red lip) with black tights, knee-high boots and a black carryall. 21 of 22 Jessica Alba WENN.com WHAT SHE WORE On her way to The Honest Company offices, Jessica Alba was spotted in a laidback-cool look: A black moto jacket over a studded black top with printed pants and buckled boots. A cherry-red tote delivered a punch of color. 22 of 22 Kristen Wiig Lisa Maree Williams/Getty WHAT SHE WORE Instead of donning a dress, Wiig worked the Anchorman 2 premiere in an all-black Martin Grant jumpsuit, styling it with a black skinny belt, a gold Saint Laurent cuff and Christian Louboutin peep-toes.