We evaluated program capacity factors associated with client outcomes in publicly funded substance abuse treatment organizations in one of the most populous and diverse regions of the United States. Using multilevel cross-sectional analyses of program data (n = 97) merged with client data from 2010 to 2011 for adults (n = 8,599), we examined the relationships between program capacity (leadership, readiness for change, and Medi-Cal payment acceptance) and client wait time and treatment duration. Acceptance of Medi-Cal was associated with shorter wait times, whereas organizational readiness for change was positively related to treatment duration. Staff attributes were negatively related to treatment duration. Overall, compared to low program capacity, high program capacity was negatively associated with wait time and positively related to treatment duration. In conclusion, program capacity, an organizational indicator of performance, plays a significant role in access to and duration of treatment. Implications for health care reform implementation in relation to expansion of public health insurance and capacity building to promote health equities are discussed.