The actress, 24, checked out of UCLA's Neuropsychiatric Hospital on Tuesday after just over three weeks, a source confirms. The judge had originally ordered Lohan to three months of in-patient treatment as part of her sentence for violating probation in a DUI case.
"She's out and doing really well," the source tells PEOPLE.
According to a source close to Lohan, the actress is now in UCLA's outpatient program, which has strict rules for patients.
"The outpatient program is just like the inpatient program, except you get to go home at night," a UCLA patient tells PEOPLE.
Due to overcrowding and good behavior, Lohan's jail term also had been cut short to 13 days instead of the three months ordered by the judge.
A hearing is set for Wednesday morning at a Beverly Hills courthouse before a new judge, Elden Fox.
RadarOnline was first to report her release from rehab.
Reporting by JENNIFER GARCIA, OLIVER JONES and KEN LEE