Associated with the dramatic increase in the numbers of women entering the criminal justice system is the recognition of the prominent role of co-occurring substance use and mental disorders (COD) in the lives of female offenders. This article reviews current research examining the prevalence and range of COD among female offenders, the variety of psychosocial problems faced by the female offender with COD, and the multiple treatment needs of women with COD who are under criminal justice supervision. Women with COD can enter the criminal justice system at several different points and, because both substance use and mental disorders carry significant risk of relapse, effective treatment approaches must address both disorders. The paper concludes with a discussion of several important treatment issues and provides suggestions regarding an agenda for future treatment and research. Copyright © 2004 John Wiley & Sons, Ltd.