NY Fashion Week: Day 1

Backstage at L.A.M.B. fellow celebrity designer Sean Combs congratulated Stefani on her latest collection. Diddy shared the front row with Stefani's son, Kingston, as well as Sophia Bush and rapper Eve, both of whom wore pieces from the L.A.M.B. line. Guests at the show received Stefani's new fragrance, L, as a gift.

-Bronwyn Barnes, reporting by Polly Blitzer and Grace Lee

See the stars at London Fashion Week on InStyleMagazine.co.UK.

L.A.M.B. creator Gwen Stefani unveiled her Spring collection for a fashion crowd that included everyone from country superstar Carrie Underwood to rap mogul P. Diddy. Even Stefani's cool kid Kingston was on hand, rocking out with dad Gavin Rossdale as the catwalkers strutted in the latest punk flavored L.A.M.B. designs. "I started crying," Stefani later said of her emotional victory lap down the runway with Kingston.

Record exec Jimmy Iovine and R&B songstress Mary J. Blige were among the after-show crowd who helped celebrate the release of Gwen Stefani's new L for L.A.M.B. fragrance at a bash hosted by In Style. Shirley Manson, Sophia Bush and Cuba Gooding also circulated at the late-night soiree, held on the rooftop of New York City's chic Gramercy Park hotel.

She wore black, but Hilary Swank looked anything but basic when she attended the 25th anniversary celebration of Calvin Klein Underwear at the company's N.Y.C. headquarters. Swank and Blood Diamond star Djimon Hounsou are the new faces-and bodies-of the label's sexy underwear line.

Guests like Kate Bosworth, Nick Cannon and Amanda Peet were offered Bellinis on arrival at N.Y.C. landmark Cipriani for the Rag & Bone show. Bosworth described her Rag & Bone look as part equestrian and part street chic.

Backstage at Rag & Bone, Mya got a quick hair touch-up at the John Frieda VIP suite before heading out to her seat in the front row. The singer admitted that she'd already given herself a manicure in the car on the way the show!

Amanda Peet

brought along longtime friend-the two met as freshman at Columbia University-and stylist Tina Chai to preview the designs at Rag & Bone. New mom Peet showed off her favorite accessory, a one-of-a-kind locket from Kaviar & Kind that was engraved with daughter Frances's name.

There were sweeping views of Central Park and a sunlit cityscape, but all eyes were on Demi Moore and Eve at a luncheon celebrating Lanvin designer Alber Elbaz. "It doesn't count as wearing white after Labor Day because it's cream, not white," said Eve of her wardrobe choice. Demi was happy to support Elbaz, who designed her wedding dress.

A bespectacled Chloe Sevigny was also among the ladies who lunched to fete Lanvin's Alber Elbaz at the FIT Couture Council event high atop Rockefeller Square in the famed Rainbow Room.

The front row at BCBG Max Azria was a family affair. "She's my little blonde twin. People always say we look alike," Tina Simpson said of doppelganger daughter Ashlee. Down the row, Martina McBride took in her first fashion show with her daughter. Singer Ciara sported an all-gray ensemble. "I love my high-waisted jeans, my high heels and my fly winter boots. So necessary, gotta have them," Ciara said of her fall must-haves.

Sophia Bush

said it took her only a few minutes to "eat breakfast, throw a little makeup on and head out the door" for the 10am BCBG show. But the One Tree Hill star-who ran into Hairspray actress Brittany Snow on her way into the tents-was already battling fashion week fatigue. "I started losing my voice and I never stop talking when I'm here, so it's not getting any better!" Bush said with a hoarse laugh.

After the BCBG show, Ashlee Simpson ditched her mom and hooked up with Fall Out Boy bassist Pete Wentz for the Rock & Republic pre-party to celebrate Fashion Rocks. Once the Gym Class Heroes took the stage for a private performance, the couple joined in with the screaming fans at Eyebeam Studios, dancing to the band's rendition of "Cupid's Chokehold" in the elevated VIP area.

Back from her summer vacation in Italy, Anne Hathaway hit the Marchesa Spring 2008 presentation at the Chelsea Art Gallery. New mom Naomi Watts and celebrity stylist Rachel Zoe were also on hand to see the latest luxe gowns from Marchesa design duo Georgina Chapman and Keren Craig.

Before hitting pal Gwen Stefani's L.A.M.B. show-and after her lunch with Demi Moore to celebrate Lanvin designer Alber Elbaz- Eve stopped by the MAC Cosmetics Fashion Lounge at the Bryant Park tents. The multi-tasking rapper also revealed her plans to reinvent her own Fetish fashion line.

Soon-to-be bride and groom Selita Ebanks and Nick Cannon upped the celebrity factor in the front row at the Alexandre Herchcovitch show. Photographer and America's Next Top Model panel member Nigel Barker was also on hand to judge the designer's spring line.

Newly minted Broadway star Lance Bass sprung up from his front row seat to strut the runway during the finale of the Nautica show in the Bryant Park tents.

KEEP CLICKING TO SEE MISCHA BARTON, DEMI MOORE AND MORE STYLISH STARS AT THE VAN CLEEF & ARPELS PARTY.