OBJECTIVE: To evaluate how a sample of outpatient substance abuse treatment units respond to organizational and environmental influences by adopting and implementing treatment services for women. DATA SOURCES: The National Drug Abuse Treatment System Survey from 1995 and 2000, a national survey of outpatient substance abuse treatment units. STUDY DESIGN: Health services for women are the dependent variables. The predictors include organizational and environmental factors that represent resource dependence and institutional pressures for the treatment unit. Logistic regression and Heckman selection models were used to test hypotheses. DATA COLLECTION: Program directors and clinical supervisors at each treatment unit were interviewed by telephone in 1995 and 2000. PRINCIPAL FINDINGS: Units that depended on specific funding for women’s programs and that depended on government funds were more likely to adopt, but not necessarily implement, women’s services. Methadone units and units that train more staff to work with women were more likely to adopt as well as implement women’s services. Private not-for-profit units were more likely to adopt some services, while for-profit units were less so. However, in general, neither for-profit nor not-for-profit units significantly implemented services. There was evidence that the odds of adopting services were greater in 2000 than 1995 for two services, but were otherwise stable. CONCLUSIONS: There is considerable variation in the adoption and implementation of women’s services. In addition, not all adopted services were significantly implemented, which could reflect limited organizational resources and/or conflicting expectations. This also suggests that referral mechanisms to these services, and therefore access, may not be adequate. Government funds and specific funds for women’s programs are important resources for the provision of these services. Women’s services appear more available in methadone units, suggesting that regulation has been influential and that the recent methadone accreditation system should be evaluated. Staff training may be one strategy to encourage implementation of these services. For the most part, the adoption of services for women did not change between 1995 and 2000.