After defining mentally disordered offenders and reviewing the problem of differentiating them from other offenders for the purposes of housing and treatment, this monograph identifies society's primary objectives in dealing with offenders. Clinical and legal issues associated with various classes of mentally ill offenders are examined. These classes are persons incompetent to stand trial, persons found not guilty by reason of insanity, and offenders whose mental illness results in their being transferred from prison to a secure hospital. Discussions of each of these classes of mentally disordered offender begins with a description of how the particular class of mentally disordered offender is identified, followed by a review of some of the theoretical and practical issues of concern to clinicians who must diagnose, treat, or care for the particular class of mentally disordered offender. Emerging legal issues associated with each class of mentally disordered offender are also identified. The discussion of practical issues focuses on the assessment, disposition, and treatment of mentally disordered offenders. A brief review of the ethical problems faced by clinicians who work with mentally disordered offenders is followed by recommendations for reform of the criminal justice system's handling of mentally disordered offenders. 195 references.