Recent years have brought an increased interest in the treatment needs of pregnant substance abusers. This article reviews the literature on this subject, providing an overview of what is known about the prevalence of substance abuse during pregnancy; the factors in women's lives, especially pregnant women, that lead to substance abuse and that facilitate and impede treatment success; and the components of successful treatment programs. The prevalence of prenatal illicit drug use is known to be about 5% of all pregnant women nationwide, with higher rates for selected subgroups. Local studies have shown much higher rates. Substance abuse is associated with poverty, with the substance abuse of significant others, and with family violence. Perinatal substance abusers experience poorer birth outcomes. The negative consequences for babies do not stop at birth; home environments may be chaotic and often children are removed from their mother's care if substance abuse continues after birth. While the literature on prevalence, correlates, and outcomes of perinatal substance abuse is plentiful, there continues to be sparse information on successful treatment approaches. Sample sizes are small and there are few studies with adequate comparison groups. The small number of outcome studies we review suggest that, as with the broader treatment literature for other populations, success (as measured by abstinence) is associated with retention. Retention is facilitated by the provision of support services, such as child care, parenting classes, and vocational training. There is no clear empirical basis for concluding that one type of treatment (for example, residential treatment) is more effective than another.