Mischa Barton Arrested!

Actress Mischa Barton, who famously played a law-breaking, troubled rich girl on the flash-in-the-pan Fox hit The O.C., has come into some trouble of her own offscreen.

The 21-year-old star was arrested late Wednesday night/Thursday morning in Hollywood for allegedly driving under the influence, possession of illegal narcotics and driving without a valid license.

"Her arrest was completed without incident," Deputy Hugo Macias of the L.A. County Sheriff Department tells OK!. "She was very cooperative."

Mischa is currently slated to host the New Year's Eve party at Cathouse in Las Vegas next week. No word yet on whether or not this arrest will put a halt to her hosting duties.

Stay tuned to OK! as this story develops.