Many states use civil commitment--a statutorily created and court-ordered form of compulsory treatment--to compel people with mental illness who become gravely disabled or dangerous to themselves or others to undergo treatment. In the last decade, many states have amended or interpreted their existing civil commitment statutes to allow for involuntary outpatient treatment. Such a law has been proposed for California. At the request of the California State Senate, the authors conducted a systematic literature review on involuntary outpatient commitment; examined the experience of eight other states including statutory analysis and in-depth interviews with attorneys, public officials, and psychiatrists; and analyzed California administrative data for all persons served by California's county contract mental health agencies. They found that involuntary outpatient commitment, when combined with intensive mental health services, can be effective in reducing the risk of negative outcomes. But whether a court order in and of itself has any effect is an unanswered question. However, there is clear evidence that intensive community-based voluntary mental health treatment can produce good outcomes. There are no cost effectiveness studies that compare the relative return on investment in developing an involuntary outpatient treatment system or focusing all available resources on developing state-of-the-art treatment systems. Either approach would require a sustained commitment by California policymakers.