KMAN Publication Inc. (KMANPUB) Applied Family Therapy Journal (AFTJ) 3041-8798 6 Serial Number 30 2025 12 01 The Effectiveness of an Acceptance and Commitment–Based Post-Divorce Co-Parenting Educational Package on Children’s Internalizing and Externalizing Disorders The Effectiveness of an Acceptance and Commitment–Based Post-Divorce Co-Parenting Educational Package on Children’s Internalizing and Externalizing Disorders 1 13 10.61838/kman.aftj.4918 EN Journal Article 2025 08 06 <p><strong>Objective:</strong> The present study aimed to examine the effectiveness of an Acceptance and Commitment Therapy (ACT)–based post-divorce co-parenting educational package on children’s internalizing and externalizing disorders.</p> <p><strong>Methods and Materials: </strong>This research employed a quasi-experimental design with pretest–posttest, a control group, and a three-month follow-up stage. The statistical population consisted of all divorced parents with children in the city of Isfahan in 2024, from which 40 participants were purposively selected and randomly assigned to an experimental group (n = 20) and a control group (n = 20). The experimental group received the ACT-based post-divorce co-parenting educational package across ten 90-minute sessions (Rabiei &amp; Mirahmadi, 2024), while the control group remained on a waiting list. The research instrument was the Child Behavior Checklist (Achenbach &amp; Rescorla, 2001), administered at three time points. Data were analyzed using repeated-measures analysis of variance and Bonferroni post hoc tests in SPSS version 26.</p> <p><strong>Findings: </strong>The results indicated that the ACT-based post-divorce co-parenting educational package led to a statistically significant reduction in children’s internalizing and externalizing disorders (p = .001). Follow-up findings further confirmed the stability of the positive effects of this intervention over time (p = .001).</p> <p><strong>Conclusion: </strong>The findings demonstrate that the ACT-based post-divorce co-parenting educational package, by strengthening emotional acceptance, enhancing psychological flexibility, and improving interparental communication patterns, can play an effective role in reducing children’s internalizing and externalizing disorders.</p> https://journals.kmanpub.com/index.php/aftj/article/download/4918/9436