Objective: Resilience has been associated with less severe psychiatric symptomatology and better treatment outcomes among individuals with posttraumatic stress disorder (PTSD) and substance use disorders. However, it remains unknown whether resilience increases during psychotherapy within the comorbid PTSD and substance use disorder population with unique features of dual diagnosis, including trauma cue-related cravings. We tested whether veterans seeking psychotherapy for comorbid PTSD and substance use disorder reported increased resilience from pre- to posttreatment. We also tested whether increased resilience was associated with greater decreases in posttreatment PTSD and substance use disorder symptoms. Methods: Participants were 29 male veterans (Mage = 49.07 years, SD = 11.24 years) receiving six-week residential day treatment including cognitive processing therapy for PTSD and cognitive behavioral therapy for substance use disorder. Resilience, PTSD symptoms, and trauma cue-related cravings were assessed at pre- and posttreatment. Results: Veterans reported a large, significant increase in resilience posttreatment (Mdiff = 14.24, t = −4.22, p textless .001, d = 0.74). Greater increases in resilience were significantly associated with fewer PTSD symptoms (β = −0.37, p = .049, sr = −.36) and trauma-cued cravings (β = −0.39, p = .006, sr = −.38) posttreatment when controlling for pretreatment scores and baseline depressive symptoms. Conclusions: Results suggest that evidence-based psychotherapy for comorbid PTSD and substance use disorder may facilitate strength-based psychological growth, which may further promote sustained recovery.