Objectives: About 65%-87% of substance use disorder patients smoke cigarettes, compared to 14% of the general adult population. Few substance use treatment centers (SUTCs) have comprehensive tobacco-free workplace (TFW) policies or offer tobacco interventions. Taking Texas Tobacco Free (TTTF) implements an evidence-based TFW program in SUTCs, including at the Billy T. Cattan Recovery Outreach Center (BTC). We present a mixed methods case study of BTC's TTTF implementation, success factors, and challenges. Methods: TTTF provided policy development assistance, training, treatment resources, and technical assistance over ∼9 months. Implementation was tailored using mixed methods. Quantitative data included surveys to stakeholders (Nmax = 7), a pre- and post-training questionnaire assessing knowledge gain, and reported quantities of tobacco use assessments (TUAs) administered and nicotine replacement therapy (NRT) provided. Qualitative data included stakeholder focus groups and interviews (18 participants). Results: All employees reported TFW policy compliance. Employees exhibited a 20% knowledge gain. Clinicians increased self-report of NRT provision and tobacco cessation counseling. During implementation, BTC administered TUAs to 171 patients and dispensed NRT to 70 of 110 tobacco-using patients. Conclusion: Qualitative findings contextualized quantitative outcomes. TTTF implementation changed clinician attitudes, knowledge, and practices regarding tobacco treatment, facilitating patient quit attempts.