Although the vast majority of seriously mentally ill persons are not more dangerous than members of the general population, there appears to be a subgroup of dangerous mentally ill persons, often characterized by a history of violent behavior, noncompliance with medications, and substance abuse. The findings indicate that current policies vis-a-vis involuntary hospitalization, involuntary medication, outpatient commitment, and the monitoring of medication compliance may need to be revised. The problem of violence by this subgroup needs to be addressed before mental health professionals can work on reducing the general societal stigma associated with serious mental illness. 2 tables and 101 references