Over the past decade, two rapidly evolving areas of criminal justice practice have garnered increasing attention from policy makers, practitioners, and researchers: the management and treatment of justice involved individuals with serious and persistent mental illness, and the challenges of managing the perceived societal risk presented by sex offenders. Yet, whereas each of these issues has independently attracted significant attention, the nexus between them has remained largely unexamined. Matters of concern include the manner in which individuals with serious mental illness may be disproportionately affected by the expanding range of restrictions placed on those with sexual offense histories, the demands for adapting traditional models of sex offender treatment and supervision for those with serious mental illness, and the manner in which public mental health agencies must adapt their systems of inpatient and community-based care to meet the needs of clients with sex offense histories. This article explores the connections between sex offending and serious mental illness, examining the magnitude and nature of the issue, the organizational and programmatic challenges facing both the public mental health and criminal justice systems, and the emergent public policy implications. The article analyzes existing research, identifies relevant gaps in our existing body of knowledge, and concludes by presenting an agenda for policy makers and researchers.