This week was all about the sexiest sheaths. And the winners are...

Jessica Alba sizzling in a Proenza Schouler shift dress at the 2010 Tribeca Film Festival Program Celebration in West Hollywood. As if the colorful, spotty print of this dress weren't fun enough, Jessica heated things up with color-coordinated heels, makeup and jewelry.

Ginnifer Goodwin ravishing in a red Valentino sheath at the 24th Genesis Awards. I love how Ginnifer breathes new life into the (yawn!) black lace trend by choosing a bright shade of red (while this dress is from the pre-fall collection, I'd say it's also perfect for spring)

Miley Cyrus rocking an asymmetrical leather sheath at "The Last Song" premiere in Los Angeles. Ruffle detailing along the shoulder of this bodyhugger adds a flirty touch.

Kristen Bell glowing in a soft lilac Alberta Ferretti dress at the Geffen Fundraiser in Los Angeles. Kristen tops off her perfectly-polished look with a pair of ankle-strap heels, which have become a huge trend on the red carpet lately.

Carey Mulligan charming in a tweed Chanel sheath at "The Greatest" premiere in Los Angeles. While this dress is no doubt sophisticated, Carey adds a youthful touch with a pair of black and gold heels with fan-like detailing along the sides and heel.

Photos (left to right): Jason LaVeris/FilmMagic; Michael Tran/FilmMagic; Lester Cohen/WireImage; John Shearer/WireImage; Paul Archuleta/FilmMagic