 Symptoms of PTSD and associated mental disorders are linked to the maintenance of tobacco dependence, premature dropout from smoking cessation treatment, and relapse to smoking following quit attempts. Many efficacious tobacco use treatments exist, but a number of barriers limit the effectiveness of current methods for delivering these treatments in VA health care settings, particularly for the mentally ill. Novel approaches to smoking cessation for individuals with PTSD are needed to circumvent these barriers by integrating evidence-based tobacco use treatment into ongoing mental health care. The research proposed here will test the effectiveness of integrating evidence-based treatment for nicotine dependence into mental health care for patients with chronic posttraumatic stress disorder PTSD. Two different methods for delivering smoking cessation treatment will be compared in a prospective, randomized controlled clinical effectiveness trial conducted at four Department of Veterans Affairs VA medical centers. Smokers undergoing mental health care for PTSD n440 will be randomly assigned to either: 1 practice guideline-concordant smoking cessation treatment that is integrated within ongoing mental health care for PTSD and delivered by mental health providers Integrated Care IC or 2 smoking cessation treatment delivered separately from PTSD treatment by smoking cessation specialists Usual Standard of Care USC. Specific aims of the proposed investigation are 1 to demonstrate that IC is more effective than USC in reducing smoking in psychiatric patients with PTSD and 2 to demonstrate that a number of treatment process variables, including the amount or dose of intervention and patient-specific factors, predict abstinence from tobacco use in smokers with PTSD. Intent-to-treat analyses and analyses for treatment completers will be conducted, using a Generalized Estimating Equations approach. If the study hypothesis is confirmed, system-wide implementation of the experimental intervention IC for veterans with PTSD would double the number of patients who stop smoking compared to the usual standard of care for tobacco use disorder. Study findings may have implications for integrating smoking cessation treatment into mental health care for patients with disorders other than PTSD. 