Two prevailing beliefs held by the public (and many professionals) connect mental illness to the criminal justice system: first, a belief that deinstitutionalization has led to criminalization of mental illness, and second, a belief that mentally ill persons are dangerous and likely to commit crimes, especially violent crimes. This chapter reviews the available empirical evidence for these beliefs. Most studies of arrest of persons with mental illness have not controlled for comorbidities, despite existing research that shows that mentally ill persons with character disorders and substance abuse are much more likely to offend and have higher arrest rates than other mentally ill persons. The public's concern about coddling criminals and the subsequent release of not guilty by reason of insanity (NGRI) offenders into the community seems to be unwarranted. Mental health and social welfare systems with severely inadequate resources try to ameliorate the effects of such deleterious social conditions.