NY Fashion Week: Day 4

It was a star-studded, black-tie affair for Ralph Lauren who celebrated 40 years in fashion at the Central Park Conservancy. Lauren's day-at-the-races-themed runway show was followed by an elegant party attended by a stunning Sarah Jessica Parker and her dapper husband Matthew Broderick. Robert De Niro, Dustin Hoffman and Martha Stewart also came out to support Lauren and his accomplishments.

-reporting by Bronwyn Barnes

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Looking chic in black and white, Janet Jackson took in the Catherine Malandrino show at the Chelsea Art Museum. Other stars including Mary J. Blige, Emmy Rossum and Sophia Bush watched as beautifully beaded necklines and organza skirts came down the runway.

As the lights started to dim, super-couple Ashton Kutcher and Demi Moore were escorted through the backstage area to the front row of the Diesel show. They joined singer Natasha Bedingfield, who took just a few minutes to swap her Rebecca Taylor outfit for a knit Diesel dress between the two shows. "I had the best seat in the house!" said Bedingfield of her spot next to Moore, who leaned over to offer her opinion of the designs on display every once in a while.

Actress-fashion designer Mary-Kate Olsen checked out the fashion scene at the Warhol Factory X Levi's X Damien Hirst collection at the Gagosian Gallery. The artist designed a denim collection for men and women, which includes a $4000 pair of jeans decorated with a skull pattern made of Swarovski crystals.

Carmen Electra

and Emmy Rossum dressed the part in their lady-like dresses to watch the parade of fearlessly feminine designs at the Rebecca Taylor show. But while Rossum probably had her spring wardrobe in mind, Electra was actually in the middle of a workday, as host of Full Frontal Fashion all week. "It's a whole different experience being out there in the middle of the tents with everything that's going on," said Electra. "I've been here a bunch of times, but usually I see a show and leave right away. I've never spent this much time here and I'm learning as I go."

Molly Sims

and Demi Moore were visions in sheer ivory dresses at the Temperley London show in the Bryant Park tents. The actresses shared some laughs while designer Alice Temperley sent her Parisian-inspired spring collection down the runway.

Mena Suvari

showed off her buzz-cut and rocker Nikki Sixx showed off his tattoos and jewelry in the front row at the Rosa Cha show. The pair got a close look at what sexy swimsuits women will be wearing next spring.

Rapper LL Cool J joined Samuel L. Jackson, Vincent Gallo and Mena Survari in an empty Chelsea parking garage for Yohji Yamamoto's Y-3 fashion show. Bold colored jackets, pants and dresses popped in the industrial setting as the sporty spring line (backed by Adidas) was revealed.

KEEP CLICKING TO SEE WHICH STYLISH STARS HIT THE SHOWS AND THE PARTIES ON DAY 3 of NEW YORK FASHION WEEK.