The introduction provides a brief history of how gender has been addressed in previous substance abuse treatment studies, along with an overview of current data on gender differences. A literature review then summarizes current information on substance abuse treatment programming for women. This is followed by a presentation of findings from analyses of data from a nationally representative sample of substance abuse treatment facilities and treatment clients involved in the Alcohol and Drug Services Study (ADSS). This study provides new information on gender differences among substance abuse treatment clients, the availability of substance abuse treatment programming for women, and the extent to which treatment services matched to women's needs improved treatment retention. Overall, special treatment programs for women were more likely to be offered in nonhospital residential or outpatient methadone facilities. Special programs for pregnant women were more likely to be offered in outpatient methadone facilities than in other types of facilities. Compared with mixed-gender facilities, women-only facilities served higher proportions of Blacks and clients whose primary source of treatment funding was public payment other than Medicaid and Medicare. Women-only facilities were also more likely to offer childcare services, prenatal care, transportation services, and special programs for women. This report clearly shows that women in substance abuse treatment have distinctive needs and that components of substance abuse treatment programming are positively linked with treatment retention, after controlling for many potential confounders. Suggestions are offered for future research. 20 tables, 8 figures, and 3 references