Lohan entered the airport courthouse dressed in a Latex mini dress and leggings, followed by her mother and her sister.
In a packed courtroom, Judge Keith Schwartz partially denied Lohan's attorney Shawn Holley's request for more time to consider a plea deal.
"This case is going to be set for preliminary hearing right now, today," he said.
The judge set a date for a preliminary hearing on April 22. On that day, it will be decided if there is enough evidence for Lohan to stand trial on the grand theft charges. If Lohan goes to trial, a judge could jail her for violating her probation from a 2007 DUI charge.
The exact terms of the deal were not disclosed, but Lohan was on probation in January when Kamofie & Co., a Venice jewelry store, accused her of taking a $2,500 necklace. Surveillance video from the store shows Lohan trying on the necklace and then leaving with it still around her neck.
Thursday's appearance marked the actress' ninth time in court in just 10 months.
Lohan has been jailed three times and sent to rehab twice for probation violations. A judge ordered Lohan to do three months of treatment at the Betty Ford Center, and it was within three weeks of her release that she was accused of stealing the necklace.
The store owners of Kamofie & Co. have announced that they will auction off that necklace and donate the proceeds to charity. But the auction will have to wait until after the case is resolved, because the necklace is being held as evidence.