Introduction: Smoking outcome expectancies were investigated in treatment-seeking military Veteran smokers with posttraumatic stress disorder (PTSD). The investigation of smoking outcome expectancies may enhance our understanding of the relationship between PTSD and cigarette smoking. Methods: Participants were 943 military Veterans with a diagnosis of PTSD who were current smokers enrolled in a randomized multisite effectiveness trial to test whether the integration of smoking cessation treatment into mental health care (integrated care) improves prolonged abstinence rates compared with referral to specialized smoking cessation clinics (usual care). Using confirmatory factor analysis (CFA), we evaluated the conceptual model of smoking outcome expectancies measured on the Smoking Consequences Questionnaire-Adult (SCQ-A) version. The Kraemer method of mediation analysis was used to investigate the role of smoking outcome expectancies in mediating relationships between PTSD symptoms and smoking behavior, tobacco dependence, and abstinence self-efficacy. Results: The CFA supported the 10-factor structure of the SCQ-A in smokers with PTSD. Relationships between measures of PTSD symptoms and tobacco dependence were mediated by the smoking outcome expectancy regarding negative affect reduction. This same smoking outcome expectancy mediated relationships between PTSD symptoms and smoking abstinence self-efficacy. Conclusions: The findings support the use of the SCQ-A as a valid measure of smoking outcome expectancies in military Veteran smokers with PTSD. Moreover, they suggest that smoking outcome expectancies may play an important role in explaining the relationship between PTSD and cigarette smoking. Published by Oxford University Press 2012.