The research has focused on four classes of mentally disordered offenders: (1) insanity acquittees, (2) defendants incompetent to stand trial, (3) mentally ill jail and prison inmates, and (4) mentally disordered sex offenders. The quantity of research has not paralleled the numbers of people in each category. Much has been written about insanity acquittees, who constitute only 8 percent of admissions of mentally disordered offenders. In contrast, mentally ill prison inmates constituted 54 percent of all admissions of mentally disordered offenders but are the subject of the smallest amount of research. Current research lacks direction, and the research directions of the past have tended to be short-lived. Future research should emphasize the following areas: (1) impact assessment of legal decisions and revised laws, (2) the prediction of dangerousness, (3) policing and the mental health system, (4) jails, (5) outcome studies, and (6) research on special groups, particularly women and youth. 60 footnotes.