Nicole Richie  turns 33 on Sunday! To celebrate the big day, we're taking a look back at Nicole's pretty radical transformation over the years, from her days of partying with Paris Hilton  and Lindsay Lohan  to her current status as a wife, mother, and all-around style star. While there may have been some bumps in the road throughout her career, it's safe to say that Nicole has come out on top. Not only is she devoted to her adorable family, but she's also a bona fide businesswoman juggling multiple fashion lines, children's charities, and stints on shows like Project Runway and #CandidlyNicole. In honor of Nicole's big day, click through to see her epic metamorphosis over the years.
Nicole showed off her patriotic side in a slinky American flag print top at a Las Vegas club opening in November 2001.
She attended a benefit party in LA in her then-signature brand of brights in March 2002.
Whoa, girl! Nicole bared (almost) all in a sheer tiger-print dress that didn't leave much to the imagination. It was actually pretty appropriate for the occasion — a Frederick's of Hollywood party in April 2002.
Nicole and Paris Hilton  partied in skimpy ensembles at a Hollywood bash in June 2002.
Before they headed to a rural farm town for the first season of The Simple Life, Fox threw Nicole and Paris a bon voyage bash that was attended by their celeb pals, including a mohawk-wearing Kelly Osbourne, in April 2003.
Nicole hit up a pre-Emmys party in September 2003 and posed for photos with some cast members from Queer Eye For the Straight Guy (remember that show?).
She and an almost-unrecognizable Taryn Manning attended a Halloween  party together in October 2003.
Nicole and Paris showed up in monochromatic looks for The Simple Life premiere party in December 2003.
They hit the stage together to present at the Billboard Music Awards in December 2003.
The duo hung out in the gifting suite during the Sundance Film Festival in January 2004 — check out that ancient flip phone!
Nicole was anything but mellow in this head-to-toe yellow look at a GM event in Hollywood back in February 2004.
Nicole and Paris were two of a (colorful) kind at their Simple Life welcome home party in April 2004.
Nicole rocked a color-coordinated look for a PlayStation 2 bash in LA in May 2004.
Nicole went for a mature suited-up look while attending a Fox event with her mom, Brenda, in June 2004.
She hit the red carpet for her Teen Choice Awards hosting gig alongside Paris in August 2004.
Nicole was given a sweet smooch by her then-boyfriend, the late DJ AM, as they sat front row for the Monique Lhuillier  runway show in September 2004.
Nicole and Paris showed up together for Mariah Carey 's annual Halloween  party in NYC back in October 2004.
She showed off a rather stunning red carpet look for the Billboard Music Awards in December 2004.
Nicole and Christina Aguilera  showed off their shiny new engagement rings — courtesy of DJ AM and Jordan Bratman, respectively — at a Roberto Cavalli  store opening in LA in February 2005.
A slimmed-down Nicole showed up in style for a Marc Jacobs  boutique opening in LA back in March 2005.
How's this for a blast from the past? Nicole and a blond Lindsay Lohan  stepped out together for a Cartier  bash in May 2005.
Nicole — with a cute new blond bob — signed autographs of her first book, The Truth About Diamonds, at an LA Barnes and Noble store in November 2005.
She and her then-stylist Rachel Zoe  attended the Marchesa  runway show together during New York Fashion Week in February 2006.
She and DJ AM (who was then her fiancé) packed on the PDA during his surprise birthday party in Las Vegas in April 2006.
Nicole was surprised with a birthday cake of her own during a Teen Vogue Young Hollywood party in LA in September 2006.
She was the belle of the ball at a launch party for the T-Mobile Sidekick in October 2006 (yes, we said T-Mobile Sidekick).
Nicole joined Rachel Zoe  at a cocktail party for designer Charlotte Ronson  in LA back in October 2006.
A dark-haired Nicole stuck close to her pal Paris Hilton  during an LA soirée in November 2006.
She flashed a peace sign at a Disney Couture party hosted by her longtime friend Kidada Jones in May 2007.
In December 2007, Nicole showed off her growing baby bump while launching The Richie Madden Children's Foundation with Joel Madden , who was then just her boyfriend.
Nicole and Joel launched another children's charity initiative together in September 2008.
Look at little Harlow! Nicole and Joel brought their baby girl to the Kidstock Music and Art Festival in LA in May 2009.
Just a year after giving birth to Harlow Madden, Nicole Richie  put her second baby bump on display at an event in LA in August 2009, this time expecting her son, Sparrow.
Joel and Nicole had a sweet date night at a Knicks game in NYC back in February 2010.
The couple kicked the glamour up a notch for the Oscars red carpet in March 2010.
Nicole signed copies of her second book, Priceless, at an LA Barnes and Noble store in October 2010.
Nicole and Joel brought their kids, Harlow and Sparrow, to a Yo Gabba Gabba! concert in LA in November 2010.
Nicole went for a vintage look when she and Joel attended Elton John's annual Oscars viewing party in February 2011.
Nicole and Joel spent a fun family day with their little ones, Harlow and Sparrow, at a Disney event in London during October 2011.
Nicole joined her Fashion Star cohorts, Elle Macpherson and John Varvatos , at the show's premiere party in NYC in March 2012.
She joined her dad, Lionel, on stage during his special Las Vegas concert in April 2012 — so sweet!
She launched her House of Harlow  collection at Sydney's David Jones store in May 2012.
Nicole attended a launch event for her fragrance, Nicole, at Macy's in LA in August 2012.
Further cementing her style star status, Nicole was honored at the Style Awards in NYC in September 2012.
She and Joel made the most of their night out during an LA Macy's event in September 2012.
Nicole expanded her empire with a special line for Macy's Impulse, and feted the launch in NYC in September 2012.
She turned it out on the red carpet at the ALMA Awards in LA in September 2012.
Nicole went for a '20s-inspired look when she attended the Baby2Baby Gala with Jessica Alba  in November 2012.
Nicole was a vision in blue when she walked the red carpet at the Golden Globes in LA in January 2013.
Nicole shared a cute moment with her godfather, Quincy Jones, during a pre-Grammys gala in LA in February 2013.
After launching a clothing line for QVC, Nicole hit the red carpet for the company's big LA bash in February 2013.
She and Joel were on hand for Elton John's annual Oscars viewing party in LA in February 2013.
Nicole spoke on stage during AOL's Digital Content NewFronts while promoting her online show, Candidly Nicole, in April 2013.
She debuted a high-fashion look for the punk-themed Met Gala in NYC in May 2013.
Nicole glammed it up for the CFDA Fashion Awards in NYC in June 2013.
She broke it down with Mario Lopez during a July 2013 appearance on Extra in LA.
Nicole sported a sequin Giorgio Armani  jumpsuit while hosting the Style Awards in NYC in September 2013.
Nicole stepped out for a Nordstrom  store opening party in LA in September 2013.
She rocked lace cat ears at a Who What Wear event in LA in October 2013.
Nicole looked gorgeous in a white cutout gown at the American Music Awards in November 2013.
Nicole and Joel made a hot red-carpet couple at the LACMA Art + Film Gala in November 2013.
Nicole and Joel stayed close while posing for photos at the Baby2Baby Gala in LA in November 2013.
A purple-haired Nicole reunited with Rachel Zoe  at the Baby2Baby Mother's Day  bash in April 2014.
In May 2014, Nicole struck a glamorous pose at the Met Gala in NYC.
Nicole promoted her VH1 reality show #CandidlyNicole at the Summer TCA Tour in LA in July 2014.
She made a stunning appearance at a trunk show for her House of Harlow  1960 collection at Bloomingdale's in NYC in September 2014.