Background: This study examined the impact of a tobacco-free grounds (TFG) policy and the California $2.00/pack tobacco tax increase on tobacco use among individuals in residential substance use disorder (SUD) treatment. Methods: We conducted three cross-sectional surveys of clients enrolled in three residential SUD treatment programs. Wave 1 (Pre-TFG) included 190 clients, wave 2 (post-TFG and pre-tax increase) included 200 clients, and wave 3 (post-tax increase) included 201 clients. Demographic and tobacco-use characteristics were first compared between waves using bivariate comparisons. Regression models were used to compare each outcome with survey wave as the predictor, while adjusting for demographic characteristics and nesting of participants within programs. Results: Odds of clients being current smokers was lower (AOR=0.43, 95%CI = 0.30,0.60) after implementation of TFG compared to baseline. Adjusted mean ratio (AMR) for cigarettes per day was lower post-TFG compared to baseline (AMR=0.70, CI=0.59, 0.83). There were no differences, across waves, in tobacco-related knowledge, attitudes, or services received by