KMAN Publication Inc. (KMANPUB) Journal of Adolescent and Youth Psychological Studies (JAYPS) 2981-2526 6 Serial Number 39 2025 11 10 Comparison of the Effectiveness of Acceptance and Commitment Therapy and Positive Psychology on Reducing Rumination and Improving Interpersonal Relationships among Lower Secondary School Female Students Comparison of the Effectiveness of Acceptance and Commitment Therapy and Positive Psychology on Reducing Rumination and Improving Interpersonal Relationships among Lower Secondary School Female Students 1 10 10.61838/kman.jayps.4538 EN Journal Article 2025 07 01 <table> <tbody> <tr> <td> <p><strong>Objective:</strong>  This study aimed to compare the effectiveness of Acceptance and Commitment Therapy (ACT) and Positive Psychotherapy (PPT) in reducing rumination and enhancing interpersonal relationships among lower secondary school female students.</p> <p><strong>Methods and Materials: </strong>This applied study employed a quasi-experimental design with a pretest–posttest control group. The statistical population included all female lower secondary school students in District 11 of Tehran during the 2024–2025 academic year. Using random selection, 45 students with low scores in rumination and interpersonal functioning were assigned to two experimental groups and one control group. The first experimental group received eight weekly 90-minute ACT sessions based on Hayes et al. (2002), and the second experimental group received nine weekly 90-minute PPT sessions adapted from Rashid and Seligman (2013). The control group received no intervention during the study period. Data were collected using the Ruminative Response Scale (Nolen-Hoeksema &amp; Morrow, 1991) and the Inventory of Interpersonal Problems (Barkham et al., 1994). Analyses were conducted using multivariate analysis of covariance (MANCOVA) in SPSS version 23.</p> <p><strong>Findings: </strong>Results revealed significant differences between the experimental and control groups on all rumination subscales, including depression (F = 75.50, p &lt; .0001, η² = .84), brooding (F = 20.30, p &lt; .0001, η² = .59), and expressiveness (F = 42.14, p &lt; .0001, η² = .75). Significant improvements were also found in interpersonal relationship subscales, such as assertiveness and sociability (F = 93.74, p &lt; .0001, η² = .87), openness (F = 38.01, p &lt; .0001, η² = .73), and supportiveness (F = 81.10, p &lt; .0001, η² = .85). No significant differences emerged between ACT and PPT in most outcomes.</p> <p><strong>Conclusion: </strong>Both ACT and PPT are effective interventions for reducing rumination and improving interpersonal functioning in adolescents, suggesting their suitability for school-based mental health promotion.</p> </td> </tr> </tbody> </table> https://www.journals.kmanpub.com/index.php/jayps/article/download/4538/8308