The average age of the 611 subjects was 27 years. The majority were white, male, unemployed at time of admission, and unmarried. Of these, 38 percent were found to have been arrested at least once in their adult lifetimes. Further, 35 percent had been arrested for felonies, while 18.9 percent were arrested for violent crimes. Analyses by the five major diagnostic groups showed that patients with a primary diagnosis of drug or alcohol abuse had the greatest overall frequency of arrests, as well as the greatest frequency of arrests for burglary, offenses against the public peace such as peace disturbance or loitering, and probation or parole violation. No significant differences between diagnostic groups were found for arrests for violent crimes. Characteristics that predicted which patients would be arrested in the year after receiving mental health services included a greater number of felony arrests, younger age, being black or a member of another minority group, and more years since first receiving public mental health care. While the arrest rates in this sample were lower than those previously found in samples of former State mental hospital patients, they are still 17 times greater than those for the same-age general population in Missouri. 5 tables and 15 references.