Nicole Richie was alone Sunday night when cops pulled her over in Burbank, Calif., and arrested her on DUI charges.

The pin-thin starlet was talking on her cell phone when cops pulled over her black Mercedes SUV, which matched a 911 caller's description of a car driving the wrong way down L.A.'s 134 freeway.

After failing a field sobriety test, Nicole was taken into custody at 4:50 am.

According to TMZ.com, the 5'1", 85-pound reality star told Glendale police she had taken Vicodin and smoked marijuana after preliminary screenings that indicated she was not under the influence of alcohol.

"Extra's" also learned Nicole was released on $15,000 bail.

Sunday night served as a painful reminder of Nicole's not-so-simple past; she faced charges of possessing heroin in 2003 before kicking her addictive habit in rehab.

Richie has also fought a serious weight disorder, and this September, she finally checked herself into a treatment center.

The young socialite wasn't the only Hollywood star stepping out over the weekend.

Super couple Jennifer Lopez and Marc Anthony sizzled and shined, even amidst new baby buzz that the couple is looking to adopt a child from Puerto Rico.

If the news is true, "Extra" wouldn't be surprised. Jennifer recently told us, "That's why everybody calls me Ma in real life!"

On Monday, Jennifer's publicist responded to the reports, telling "Extra" the stories are not true.

J Lo and Marc were among the glitzy and glamorous guests at Tom Cruise and Katie Holmes' post-wedding celebration Saturday night in Beverly Hills.

Steven Spielberg pulled up in a Bentley with wife Kate Capshaw, as Will Smith and wife Jada arrived in a $350,000 Maybach.

Orlando Bloom turned heads as he drove up in a yellow V.W., as did the arrival of Penélope Cruz, Tom's former flame.

"Penélope had come over to meet Suri, so this is not unusual that she would be there," dished People magazine's JD Heyman of Tom and Penélope.

Another famous Hollywood couple kept the holiday spirit alive over the weekend, toting their adorable family with them as they took on the Big Apple.

On Friday night, Brad Pitt, Angelina Jolie and the kids braved a photo frenzy in New York while shopping at an art store.

Brangelina put on the glitz Saturday night as they stepped out for a date night at Robert De Niro's place.