A major challenge in studying the relationship between mental disorder and violent behavior lies in eliminating spuriousness from the analysis because the two share many of the same risk factors. This study uses nationally representative data from the Survey of Inmates in State and Federal Correctional Facilities 1997 (N = 17,248) in an attempt to isolate causal effects of mental health problems on violent behavior among criminal offenders. Controlling for respondents' past violent behavior and other relevant factors, the research found that a history of mental health treatment is more strongly associated with assaultive violence and sexual offenses than with other types of crimes. In addition, there is support for a deviance hypothesis: Offenders with mental health problems tend to engage in more deviant types of criminal acts than those without such problems.