Mental health courts (MHCs) have become widespread in the United States as a form of diversion for justice-involved individuals with mental illness. Sanctions and incentives are considered crucial to the functioning of MHCs and drug courts, yet with little empirical guidance to support or refute their use, and there are no definitions of what they are. The use of sanctions and to a lesser degree incentives is the focus of this article, with particular emphasis on jail sanctions. Subjects are participants (n = 447) in four MHCs across the United States. Results show that jail sanctions are used in three of four MHCs, and other sanctions are similarly used across the four MHCs. Participants charged with "person crimes" are the least likely to receive any sanctions, including jail, whereas those charged with drug offenses are most often sanctioned. The factors associated with receiving a jail sanction are recent drug use, substance use diagnosis, and drug arrests; being viewed as less compliant with court conditions, receiving more bench warrants, and having more in-custody hearings; and MHC program termination. No personal characteristics are related to receiving sanctions. Knowing which MHC participants are more likely to follow court orders and avoid sanctions, and identifying those who have difficulty adhering to court conditions, can help guide court officials on adjusting supervision, perhaps avoiding reoffending and program failure.