The major standard for involuntary detention in all recently revised mental health codes is dangerousness. More covertly, this standard is also used throughout the criminal justice system for the continued detention of various classes of offenders. The use of this standard for detention is characterized by a huge gap between ever-increasing legislation and the empirical data indicating the inabilities of all groups, particularly psychiatrists, to accurately make estimations of future assaultive behavior. This research centers on two points in this controversy: (1) the questionable uses of studies of the arrest rates of ex-mental patients, and (2) the benefits of using situational factors in making the predictions mandated by the dangerousness standard. All mental patients (N equals c.250) and all offenders (N equals c.900) from Albany County, New York in 1975 and 1968 and a sample of all mental patients discharged statewide from New York State Psychiatric Centers in 1975 and 1968 (N equals c.2,000 each) will be designated. Analyses will attempt to demarcate those subgroups of mental patients and offenders most appropriate for a longer term community follow-up examining the rate and circumstances of violent behavior to provide comparable arrest rates for violent offenses for mental patients and offenders in the same jurisdiction which can be compared with those for the general population. In addition to drawing out the relevant policy implications for the application of the dangerousness standard among the mentally ill and offenders, this project will develop a continuation proposal focusing on the roles of situational factors in incidents of violent behavior among the mentally ill, offenders and the general population.