Abstract
<title>Abstract</title> <p> <bold>Background:</bold> Spouses of military personnel with post-traumatic stress disorder (PTSD) are at increased risk of marital difficulties, emotion regulation problems, and secondary traumatic stress symptoms. Acceptance and Commitment Therapy (ACT) has shown promise in improving psychological functioning across a range of populations; however, evidence regarding its effectiveness among military spouses remains limited. This study investigated the effectiveness of ACT on marital functioning, emotion regulation difficulties, and secondary traumatic stress symptoms among wives of soldiers with PTSD. <bold>Methods:</bold> This randomized controlled trial was conducted in Yazd, Iran, between September 2024 and May 2025. Fifty-two wives of military personnel with clinically significant PTSD were recruited and randomly assigned to either an ACT intervention group (n = 26) or a wait-list control group (n = 26). The intervention consisted of seven weekly ACT group sessions lasting 60–90 minutes. Outcomes were assessed at pretest, posttest, and three-month follow-up using the ENRICH Marital Satisfaction Scale (ECS), the Difficulties in Emotion Regulation Scale (DERS), and the Secondary Traumatic Stress Questionnaire (STQ). Data were analyzed using mixed repeated-measures analysis of variance. <bold>Results:</bold> No significant baseline differences were observed between groups (all p > .05). Significant group × time interaction effects were found for marital functioning, F(1.65, 82.40) = 186.90, p < .001, ηp² = .789, secondary traumatic stress symptoms, F(1.95, 97.23) = 117.28, p < .001, ηp² = .701, and emotion regulation difficulties, F(1, 50) = 8.04, p = .007, ηp² = .138. Participants receiving ACT demonstrated substantial improvements in marital functioning and significant reductions in secondary traumatic stress symptoms and emotion regulation difficulties compared with the control group. Bonferroni-adjusted comparisons indicated that improvements from pretest to posttest were maintained at the three-month follow-up. <bold>Conclusions:</bold> Acceptance and Commitment Therapy was effective in improving marital functioning and reducing emotion regulation difficulties and secondary traumatic stress symptoms among wives of military personnel with PTSD. The maintenance of treatment gains at follow-up suggests that ACT may provide a sustainable and clinically useful intervention for enhancing psychological well-being and family functioning in military families affected by PTSD. <bold>Trial Registration</bold> Iranian Registry of Clinical Trials (IRCT) IRCT20210708051815N3, registered on 15 July 2026. Retrospectively registered. </p>