INTRODUCTION: Certain psychiatric populations have especially low smoking cessation rates. This highlights the need to identify smoking treatments that increase cessation rates by addressing factors thought to impede their success. Behavioral activation (BA) targets anhedonia (i.e., reward insensitivity), which is linked with difficulties in quitting smoking and that is especially common and severe amongst mental health populations, including those with posttraumatic stress disorder (PTSD). Thus, BA has potential to increment the effectiveness of standard smoking cessation treatment for people with PTSD. METHODS: A randomized clinical trial for US military veterans with PTSD evaluated 8-weeks of behavioral activation versus health-smoking education counseling (contact-control) when each was used as an adjuvant to standard smoking cessation counseling and combination nicotine replacement therapy (nicotine patch + nicotine lozenge or nicotine gum). The primary outcome was biochemically confirmed 7-day point-prevalence abstinence 26-weeks after the target quit day. RESULTS: Of 124 participants randomized (mean [SD] age 49 years [12.6], 109 male [88%]), 68 (54.8%) provided final follow-up data. Intent-to-treat analyses showed 17 participants (13.7%) had biochemically confirmed abstinence at 26-weeks (16.1% self-reported abstinence). There was no significant main effect of BA (15.9%, 10/63) vs. control adjuvant counseling (11.5%, 7/61) on biochemically confirmed abstinence at 26-weeks, nor on self-reported abstinence at 4-, 12-, 20-, or 26-weeks. CONCLUSIONS: BA intervention did not improve smoking cessation rates more than an attention-control condition when each was paired with standard cessation counseling and medication and delivered to US veterans with PTSD. Smoking treatment was not associated with psychiatric symptom exacerbation. IMPLICATIONS: Behavioral activation therapy has proven effective in treating people with mental health disorders and may be effective as a smoking treatment. This randomized clinical trial compared behavioral activation with intensity-matched attention-control therapy when each was used as an adjuvant to standard smoking cessation treatment (counseling + nicotine patch and lozenge or gum) among US military veterans with posttraumatic stress disorder (PTSD). Behavioral activation therapy did not produce higher smoking abstinence rates than an attention-contact control therapy when each was paired with standard smoking cessation treatment delivered to patients with PTSD. Smoking treatment was not associated with worsening of psychiatric symptoms.