"You're in a different situation now that a felony has been filed," Superior Court Judge Keith Schwartz scolded Lohan after she entered the plea through her attorney. "Everybody else has to follow the law. You're no different than anyone else. So please, don't push your luck."
Saying it appeared Lohan had violated her probation in a 2007 drunken driving case, Schwartz set bail at $40,000 and warned that if she was accused of breaking the law while free, he would have her held without bail.
Lohan, 24, posted bail and was released about an hour after the hearing. She spoke little during the arraignment, except to acknowledge her name and that she understood the charge and possible consequences.
Lohan could face up to three years in state prison if eventually convicted of stealing the necklace in January from a Venice Beach store.
The "Mean Girls" star has remained in the spotlight throughout her legal problems. Wednesday, she was met by a swarm of photographers and TV cameras when she arrived at the courthouse in a white dress and sunglasses.
Until now, Lohan has struggled with the terms of her probation in the DUI case but has not been charged with other crimes.
The former Disney star has been a courthouse regular since May, when another judge determined she had violated her probation by missing weekly alcohol education classes.
She was sent to jail and rehab after missing a hearing then granted early release from both facilities. Within weeks, however, she failed a drug test and was briefly returned to jail before spending the next three months in rehab.
Lohan's three stints in jail in the past three years have all been shortened by overcrowding and the fact that she could not be held without bail on a misdemeanor.
The jewelry case is not Lohan's only legal concern. Prosecutors in Riverside County are considering whether to charge the actress with battery for an altercation with a rehab worker at the Betty Ford Center in December.
The worker was fired after giving an on-camera interview to celebrity website TMZ, but district attorney's spokesman John Hall has said the allegation against Lohan was under review.
Schwartz was the third judge in seven months to warn the actress she was facing serious jail time if she broke the law.
Defense attorney Shawn Chapman Holley said Wednesday that Lohan was interested in an early disposition program where she could work out a deal to keep the case from going to trial.
Holley also said Lohan has received good reports from her probation officer and had not failed any recent drug screens.
Prosecutor Danette Meyers rejected the idea that Lohan has been well-behaved.
"A good probationer doesn't pick up a new case," Meyers said.
Another hearing was set for Feb. 23.