Iranian Association for Intelligence and Talent Studies International Journal of Education and Cognitive Sciences 3041-8828 In Press 2026 11 01 Effectiveness of Acceptance and Commitment Therapy on Psychological Well-Being in Patients with Cancer Effectiveness of Acceptance and Commitment Therapy on Psychological Well-Being in Patients with Cancer 1 13 EN Journal Article 2026 03 03 <p><strong>Purpose: </strong>This study aimed to determine the effectiveness of Acceptance and Commitment Therapy (ACT) in improving the psychological well-being of patients diagnosed with cancer.</p> <p><strong>Materials and Methods:</strong> This quasi-experimental study employed a pretest–posttest design with a control group and a follow-up assessment. The statistical sample consisted of 60 patients with cancer who were selected through purposive sampling and assigned to three groups of 20 participants. Participants in the intervention groups received an ACT-based intervention consisting of eight 45-minute sessions delivered over one month, whereas the control group received no psychological intervention during the study period. Psychological well-being was assessed using Ryff’s 84-item Psychological Well-Being Scale (1989) at the pretest, posttest, and follow-up stages. The collected data were analyzed using inferential statistical procedures in SPSS version 25.</p> <p><strong>Findings:</strong> The inferential analysis demonstrated a statistically significant difference between the intervention and control groups in posttest psychological well-being scores. Participants who received Acceptance and Commitment Therapy showed significantly higher levels of psychological well-being than those in the control group. The intervention produced a very large effect size (η² = 0.935), indicating that a substantial proportion of the variance in post-intervention psychological well-being was attributable to the therapeutic intervention. The follow-up analysis further showed that the improvement in psychological well-being was maintained after the completion of treatment, suggesting the stability and durability of the intervention effects over time.</p> <p><strong>Conclusion:</strong> Acceptance and Commitment Therapy is an effective psychological intervention for enhancing psychological well-being among patients with cancer. By promoting psychological flexibility, acceptance of difficult internal experiences, present-moment awareness, and engagement in value-oriented behaviors, ACT may help patients cope more adaptively with the psychological consequences of cancer. Therefore, this intervention may be incorporated into psychosocial rehabilitation and supportive care programs for patients with cancer.</p> https://journalecs.com/index.php/ecs/article/download/431/392