Inside Nicole Richie's Star-Studded 30th Birthday Party

Nicole Richie's wild party girl days may be over -- but the reality star turned designer and mom made sure her 30th birthday was unforgettable!

On Wednesday -- her big 3-0 -- Richie gathered a bevy of A-list pals for a fete at a deluxe suite at the Beverly Wilshire in Beverly Hills.

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Among the guests at the black-and-white themed party? DJ (and Lindsay Lohan ex) Samantha Ronson arrived with a huge crew, wearing skinny jeans, a black leather jacket and a feathered fedora. Fellow fashionista Mary-Kate Olsen (in a flapper-inspired dress, boyfriend blazer and an oversized backpack) turned up with three pals.

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Benji Madden, the twin brother of Richie's husband Joel Madden, arrived solo. Music super-producer Quincy Jones -- who worked with Nicole's father Lionel Richie on his blockbuster 80s hits -- was also on hand for the fete.

"I can't believe the outpour of birthday love I am getting on twitter today!" Richie wrote on her Twitter account Wednesday. "From the bottom of my heart (& the top), THANK YOU SO MUCH!"

Richie also gave a sneak peek of her footwear for the evening: A tottering, spiked stiletto shoe. "Gonna be that kind of night," she teased.

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And the married mother of two (Harlow, 3, and Sparrow, 2) stunned for her big night out. Posing in a TwitPic with hubby Madden, 32, Richie wore a vintage, 1920s-inspired red dress, her long blonde locks in a half-bouffant.

"Mr. & Mrs Over The Hill," she joked.