ABSTRACTBackground: Differences in tobacco use behaviors have been identified between Latinos and non-Latino whites in the general US population. Little is known about cigarette smoking and quitting behaviors of Latinos in treatment for substance use disorders (SUDs), who represent two major tobacco-vulnerable groups. Objectives: To compare, in a national sample of persons enrolled in SUD treatment, demographic, drug use, and smoking and quitting prevalence and behaviors between Latinos and non-Latino whites. Methods: We surveyed 777 SUD treatment clients, sampled from 24 clinics selected at random from the National Institute on Drug Abuse Clinical Trials Network (Latino client n = 141; 40% female). We then conducted univariate and multivariate analyses to identify correlates of smoking behaviors by Latino/non-Latino white ethnicity. Results: Latinos’ smoking prevalence resembled that of non-Latino whites (78.7% vs. 77.4%). In regression analyses, Latino smokers (n = 111) tended to smoke fewer cigarettes per day (CPD) than non-Latino white smokers (n = 492); were more often nondaily smokers and menthol smokers; more often reported a smoking quit attempt in the last year; and tended to report higher numbers of past-year quit attempts. Among Latino smokers, those with less education and those reporting opioids as their primary drug of use reported higher CPD. Conclusions: Latinos in SUD treatment are at equally high risk of being current heavy smokers as compared to non-Latino whites in SUD treatment. At the same time, Latinos in SUD treatment exhibit ethnic-specific smoking and quitting behaviors that should be considered when designing smoking interventions for this group.