The mentally disordered offenders studied included 83 with a substance abuse history, 540 with a psychiatric history, and 141 with a combined substance abuse and psychiatric history. A sample of 544 violent offenders with no mental health background formed the comparison group. The offenders with mental health backgrounds, especially those with substance abuse problems, had more extensive criminal histories than other offenders. All groups of mental health clients were more often arrested for breaches of public order. Types of offenses varied among different groups. Differences in offenses involving convictions paralleled those found in criminal histories. Felony-related violence was less characteristic of offenders with mental health backgrounds than of other violent offenders. Eccentric offenses were rare among offenders with no mental health background, while persons with a psychiatric history were overrepresented in all categories of eccentricity. Many violent incidents by disturbed offenders showed ineffectual or counterproductive behavior. In addition, almost two-thirds of the offenders with substance abuse histories were intoxicated at the time of offense. Findings indicated relevance of some clinical attributes of disturbed offenders to some types of offenses. Treatment implications and other recommendations, tables, and 21 reference notes.