An overview is presented of the research about mental illness and criminality. The findings were confusing and conflicting, mainly because of methodological problems in the research. However, general conclusions included the following: psychiatric patients tended to get arrested at a higher rate; factors associated with offenses by mentally ill people were the same as those associated with offenses by members of the general public; there was no uniform rate of offending, and the high rate of offenders may not be comparable to the majority of patients; the problems experienced were likely a function of the system, with less accessible community resources contributing to a diversion of some mentally ill patients into the criminal justice system.