Actress Lindsay Lohan pleaded not guilty on Wednesday to stealing a $2,500 necklace from a Los Angeles jewelry store.

Dressed all in white for a brief court appearance, Lohan, 24, was charged with a single count of felony grand theft. If convicted, the "Mean Girls" star could be sent to prison for up to three years, prosecutors say.

Lohan is accused of walking out of a Los Angeles jewelry store without paying for a gold designer necklace in January -- just three weeks after ending her fifth stint in drug and alcohol rehab in three years.

Lohan lawyer entered the not guilty plea for the actress in front of a packed courtroom and cameras televising the hearing.

Friends have said Lohan believed the necklace, which has been returned to police, was on loan.

Lohan, dressed in a long-sleeved white dress and looking calm, was expected to be released on bail, set at $20,000, later on Wednesday after being booked and photographed by court officials.

Wednesday's felony grand theft charge was the most serious allegation yet against the actress in more than three years of failed drug tests, brief spells in jail and missed court appearances.

"You are no different than anyone else, so please don't push your luck," judge Keith Schwartz told Lohan, saying the felony charge was different from previous charges against her because it is considered a more serious crime with greater punishment.

Lohan is still on probation for a 2007 drunk driving and cocaine possession offense that has halted her once promising Hollywood movie career. If convicted of the theft charge, she would also be in violation of probation, which would mean even more jail time for the troubled actress.

In early January, she completed a court-ordered three month stint in rehab and appeared to have renounced a former lifestyle that revolved around night clubs and partying.

Lohan also faces possible criminal charges for an alleged attack on a worker while in her recent rehab at the Betty Ford Center in southern California. That case is under review by prosecutors.

The actress made her name as an 11-year-old in the Disney movie "The Parent Trap" and went on to have hits with "Freaky Friday" and "Herbie Fully Loaded".

But her seemingly constant legal troubles have prevented Lohan from reviving her career. Her latest stint in rehab cost her the lead role in a planned movie about 1970s porn star Linda Lovelace. Her last movie, the action comedy "Machete" released in September 2010, made just $26.6 million at U.S. box offices.