FOLLOWING A BRIEF DISCUSSION OF THE PUBLIC IMAGE OF EX-MENTAL PATIENTS AS FREQUENT PERPETRATORS OF CRIME, PARTICULARLY VIOLENT OFFENSES, THE METHODOLOGY OF A STUDY OF THIS ISSUE IS DESCRIBED. ONE SAMPLE STUDIED CONSISTED OF 1,938 MENTAL PATIENTS RELEASED FROM NEW YORK STATE PSYCHIATRIC CENTERS IN FISCAL 1975; AND A SECOND SAMPLE WAS COMPOSED OF 1,920 EX-PATIENTS RELEASED FROM NEW YORK STATE PSYCHIATRIC CENTERS IN 1968. THE 1968 SAMPLE WAS SELECTED AS REPRESENTATIVE OF MENTAL PATIENTS RELEASED BEFORE MAJOR DEINSTITUTIONALIZATION OCCURRED. FOR ALL PERSONS IN THE TWO STUDY GROUPS, HOSPITALIZATION RECORDS WERE OBTAINED FROM THE STATE DEPARTMENT OF MENTAL HEALTH, AND CRIMINAL RECORDS WERE SECURED FROM THE STATE DIVISION OF CRIMINAL JUSTICE SERVICE. THE AVERAGE FOLLOWUP PERIOD AFTER RELEASE FOR EACH SAMPLE WAS 19 MONTHS. IN ORDER TO DETERMINE WHAT FACTORS MIGHT BE ASSOCIATED WITH SUBSEQUENT ARREST FOR VIOLENT CRIME, 23 VARIABLES OBTAINABLE FROM THE DATA EXAMINED WERE CONSIDERED. RESULTS ARE SAID TO INDICATE THE FEW PEOPLE RELEASED FROM STATE MENTAL HOSPITALS WERE INVOLVED IN CRIME, AND THOSE EX-MENTAL PATIENTS MOST APT TO BE ARRESTED FOR VIOLENT CRIMES ARE THOSE WITH CHARACTERISTICS SIMILAR TO THOSE IN OFFENDER POPULATIONS IN GENERAL; I.E., YOUNGER INDIVIDUALS WITH LENGTHY PRIOR CRIMINAL RECORDS. ALTHOUGH MENTAL HOSPITALIZATION IS, DUE TO NEW YORK STATE POLICY, AN EVER-INCREASING OCCURRENCE FOR THOSE CHARGED WITH CRIMINAL ACTIVITY, IT IS CONCLUDED THAT MENTAL ILLNESS PER SE IS NOT AN INCREASINGLY COMMON FACTOR IN VIOLENT CRIME; HOWEVER, UNDER THE PRESENT SYSTEM OF EXPANDING THE PLACEMENT OF CRIMINAL OFFENDERS IN MAXIMUM SECURITY MENTAL FACILITIES, THOSE TREATED IN THESE TYPES OF MENTAL FACILITIES WOULD EXPECTEDLY BE A HIGH RISK FOR VIOLENT BEHAVIOR UPON RELEASE. STUDY DATA AND REFERENCES ARE PROVIDED. (RCB)