Biquarterly Journal of studies and psychological news in adolescents and youth Fall and Winter 2022, Volume 2, Issue 2(3), 32-37 The Effectiveness of Mindfulness-based Group Therapy (MBGT) on Cognitive Emotion Regulation (CER) in Female Adolescents Behnaz Pishkhor, Abolghasem Khoshkonesh, Ali Zadehmohamadi, Saeid Ghanbari, Leila Bayat Abstract Background and Aim: The role of emotion regulation in mental illness and learning and functional abilities of adolescent students has been confirmed today and is an important basis for the emergence of emotional and behavioral disorders during adolescence. Accordingly, this study was conducted to determine the effectiveness of mindfulness- based group therapy (MBGT) on cognitive emotion regulation (CER) in female adolescents. . Methods: The study had a pretest-posttest design with a control group and a two-month follow-up. The statistical population included all high school students in Saveh city (Markazi province) in the academic year 2016-2017, from which 30 people (15 in the experimental group and 15 in the control group) were selected by cluster sampling and randomly assigned to experimental and control groups. The study tool was the Cognitive Emotion Regulation Questionnaire (CERQ) developed by Granefski et al. (2001). The experimental group received eight sessions of mindfulness training, and the control group received no intervention. Data were analyzed using repeated-measures ANOVA. Results: The results suggested that MBGT affected CER in female adolescents and that this effect was stable in the follow-up phase. The results also indicated that MBGT increased positive CER and decreased negative CER (P = 0.01). Conclusion: According to the findings, counselors and psychologists are recommended to use MBGT as an effective method to increase positive CER in female adolescents. Received: 22.05.2021 Revision: 08.08.2021 Acceptance: 27.08.2021 Keywords: Mindfulness, Cognitive Emotion Regulation (CER), Female adolescents How to cite thisarticle: Pishkhor, B., Khoshkonesh, A., Zadehmohamadi, A., Ghanbari, S., & Bayat, M. The Effectiveness of Mindfulness-based Group Therapy (MBGT) on Cognitive Emotion Regulation (CER) in Female Adolescents. Bi-Quarterly Journal of studies and psychological news in adolescents and youth, 2022, 2(2): 32-37 Article type Original research 1. Behnaz Pishkhor, M.A Counseling, Faculty of Psychology and Educational Sciences, Shahid Beheshti University, Tehran, Iran, 2. Abolghasem Khoshkonesh, Assistant Professor, Department of Clinical Psychology and Health, Faculty of Psychology and Science, Shahid Beheshti University, Tehran, Iran, 3. Ali Zadehmohamadi, Associate Professor, Department of Basic Studies, Family Research Institute, Shahid Beheshti University, Tehran, Iran, 4. Saeid Ghanbei, Assistant Professor, Department of Developmental Educational Psychology, Faculty of Psychology and Educational Sciences, Shahid Bashti University, Tehran, Iran, 5. Leila Bayat, M.Sc., Criminal Law and Criminology, Faculty of Law and Political Science, University of Tehran, Tehran, Iran Correspondence related to this article should be addressed to Behnaz Pishkhor, M.A Counseling, Faculty of Psychology and Educational Sciences, Shahid Beheshti University, Tehran, Iran Email: Behnaz.pishkhor@yahoo.com