NY Fashion Week: Day 3

Jessica Simpson

Jessica Simpson

made her first fashion week appearance, in a curve-hugging Cavalli dress, at the opening party for the new Just Cavalli flagship store in New York City. Flashbulbs continued to go wild as more stylish stars like Jennifer Lopez and Ashlee Simpson made their way into the party.

-reporting by Bronwyn Barnes and Polly Blitzer

DAILY COVERAGE! CHECK IN WITH INSTYLE.COM ALL WEEK FOR INSIDE ACCESS TO THE FASHION TENTS AND PARTIES, AND A PEEK AT THE CELEBS IN THE FRONT ROW!

Roberto Cavalli and Jennifer Lopez

Not looking a bit tired since her fiery performance at Fashion Rocks, Jennifer Lopez glowed on the arm of designer Roberto Cavalli as they arrived for the opening bash of his new Just Cavalli boutique.

Ashlee Simpson

Ashlee Simpson

ditched her black jeans and revealed her great gams in a sexy black Just Cavalli dress with plunging neckline. The pop star joined her sister at the store-opening party where the DJ set the perfect mood, spinning '80s hits in the neon-heavy boutique.

Nicole Richie and Molly Sims

Security ushered in the fashionistas before escorting Nicole Richie to her prime seat at the Max Azria show. The crowd gasped as Nicole, in a flowing black halter dress, sat down next to Molly Sims to take in the chic looks from the Italian designer. "I wanted to do the red lip!" said Sims when asked what inspired her glam makeup.

Jamie-Lynn Sigler and LeAnn Rimes

Jamie-Lynn Sigler

and LeAnn Rimes took their seats in the crisp, white tent for a first look at the J. Mendel spring collection, which included plenty of ethereal gowns. "We're sort of going into fall, but it's a very hot New York day-I'm sort of slowly inching into it," said Sigler of her attempts to get into a cooler state of mind despite the warm temperatures.

Kate Bosworth

Kate Bosworth

showed off her feminine side in a bold fuchsia dress at the Thakoon show, after sporting a crisp white menswear-inspired shirt and jacket at the Rag & Bone show on Wednesday. Other stars checking out Thakoon's colorful spring collection included Amanda Peet and Joy Bryant.

Lindsay Sloane and Sarah Michelle Gellar

Sarah Michelle Gellar

attended the Vera Wang show with best friend, actress and first-time fashion show attendee Lindsay Sloane. How did Gellar prepare Sloane for the frenetic experience? "We had mimosas backstage," said Gellar. Instead of the usual techno-beats, Wang opened her show with the Beatles' "Here Comes the Sun," as soft amber lights gradually brightened. A long time supporter of Wang's, Gellar said, "Vera was the first person to ever lend me a dress when no one else would."

Demi Moore

Demi Moore

, a welcomed and stunning fashion week staple, abandoned the tents for the Proenza Schouler show, held at the Park Avenue Armory. The actress has also made appearances at the Miss Sixty show, the Lanvin luncheon and the Van Cleef & Arpels party.

Kendu Isaacs and Mary J. Blige

Mary J. Blige

and her husband Kendu Isaacs sat front row at the Baby Phat and KLS (Kimora Lee Simmons) Collection show. Instead of the Bryant Park tents, Kimora opted for an all out Saint-Tropez-themed show at the famed Roseland Ballroom. As for Blige, she was thrilled to be in the Big Apple, saying, "New York is at its finest [during fashion week] and I love getting my fashion game on."

Nick Cannon and Selita Ebanks

Also at the Baby Phat and KLS show were engaged pair, Nick Cannon and Selita Ebanks. Cannon graciously obliged the Saint-Tropez-chic attire request on the show's passport invitation by wearing a tropical-print hoodie. Guests then headed to an extravagant after-party at Guastavino's where they were each gifted with a green gemstone-and-diamond bracelet.

Diane Kruger and Joshua Jackson

Stylish couple Diane Kruger and Joshua Jackson fit right in at a fashion week party in the Soho Prada emporium, where indie band The Hours performed. Also in the crowd were Mary-Kate and Ashley Olsen, and cutting-edge artist Damien Hirst, who helped the luxe label redecorate with skull-motif wallpaper just for the event. The pretty party guests gobbled up hot dogs and burgers-no mini versions here, all of the appetizers were more than bite-sized-and washed them down with cold beer.

KEEP CLICKING TO SEE WHICH STYLISH STARS HIT THE SHOWS AND THE PARTIES ON DAY 2 of NEW YORK FASHION WEEK.