Article Abstract Objective: To evaluate the impact of concurrent treatments for substance use disorder and nicotine-dependence for stimulant-dependent patients. Method: A randomized, 10-week trial with follow-up at 3 and 6 months after smoking quit date conducted at 12 substance use disorder treatment programs between February 2010 and July 2012. Adults meeting DSM-IV-TR criteria for cocaine and/or methamphetamine dependence and interested in quitting smoking were randomized to treatment as usual (n = 271) or treatment as usual with smoking-cessation treatment (n = 267). All participants received treatment as usual for substance use disorder treatment. Participants assigned to treatment as usual with concurrent smoking-cessation treatment received weekly individual smoking cessation counseling and extended-release bupropion (300 mg/d) during weeks 1-10. During post-quit treatment (weeks 4-10), participants assigned to treatment as usual with smoking-cessation treatment received a nicotine inhaler and contingency management for smoking abstinence. Weekly proportion of stimulant-abstinent participants during the treatment phase, as assessed by urine drug screens and self-report, was the primary outcome. Secondary measures included other substance/nicotine use outcomes and treatment attendance. Results: There were no significant treatment effects on stimulant-use outcomes, as measured by the primary outcome and stimulant-free days, on drug-abstinence, or on attendance. Participants assigned to treatment as usual with smoking-cessation treatment, relative to those assigned to treatment as usual, had significantly better outcomes for drug-free days at 6-month follow-up (χ21 = 4.09, P < .05), with a decrease in drug-free days from baseline of −1.3% in treatment as usual with smoking-cessation treatment and of −7.6% in treatment as usual. Participants receiving treatment as usual with smoking-cessation treatment, relative to those receiving treatment as usual, had significantly better outcomes on smoking point-prevalence abstinence (25.5% vs 2.2%; χ21 = 44.69, P < .001; OR = 18.2). Conclusions: These results suggest that providing smoking-cessation treatment to illicit stimulant-dependent patients in outpatient substance use disorder treatment will not worsen, and may enhance, abstinence from nonnicotine substance use. Trial Registration: ClinicalTrials.gov identifier: NCT01077024 J Clin Psychiatry © Copyright 2013 Physicians Postgraduate Press, Inc. Submitted: March 1, 2013; accepted July 15, 2013. Online ahead of print: December 10, 2013 (doi:10.4088/JCP.13m08449). Corresponding author: Theresa M. Winhusen, PhD, University of Cincinnati, 3210 Jefferson Ave, Cincinnati, OH 45220 (winhusen@carc.uc.edu).