Credit: Charley Gallay/WireImage

Stephanie Pratt is going to rehab.

The Hills star, 23, pleaded not guilty to misdemeanor DUI Friday in a Los Angeles court and agreed to enroll in a 30-day residential rehab facility.

She was arrested Oct. 18 in Hollywood after driving home from a birthday party for Holly Montag.

If convicted, Pratt faces up to six months in jail and a $1,000 fine.