Shahroud University of Medical siences International Journal of Health Studies 2423-6594 2022 05 08 The Effectiveness of Schema Therapy on Aggression and Emotion Dysregulation in Adolescent Girls with Self-harm 10.22100/ijhs.v9i1.954 eng Mahboube Yavari Ramshe Master of Cilinical Psychology, Department of Psychology, Science and Reasearch Branch, Islamic Azad University, Tehran, Iran. Ramshe Mahshid Sharafi Master of Clinical Psychology, Faculty of Literature and Humanities, Department of Psychology, Tehran Azad University of Research Sciences, Tehran, Iran. Mohadeseh Nazari Master student of general psychologist, Faculty of literature and Humanities Department of counseling Rasht university, Rasht, Iran. Ali Mohammadi Master of Industrial and Organizational Psychology from Marvdasht Islamic Azad University, Marvdasht , Iran. Elham Ftros Psychology Department Graduated Student, College of Humanities, Qomayn Branch, Islamic Azad University, Qomayn, Iran. Javad Seyed Jafari Ph.D. candidate in Psychology, Allameh Tabataba'i University, Tehran, Iran. 2022 05 10 2022 05 04 Background: Many interventions currently recommended for young people whose self-harm are clinic-based, delivered by mental health clinicians, and primarily aimed to address the underlying mood and personality disorders. This study aimed to evaluate the effectiveness of schema therapy on aggression and emotion dysregulation in an adolescent girl with self-harm. Methods: The research method was semi-experimental with pre-test & post-test design with the control group. The study population included all female patients with self-harm who had been referred to public and private Center for Psychiatry and Psychology, Aram, during November to January in Tehran District 3, Iran, in 2021. 30 people were selected through purposive sampling method and randomly divided into two groups of experimental (n=15) and control (n=15). Questionnaires such as Aggression questionnaire (AGQ) and The Difficulties in Emotion Regulation Scale (DERS) were used for data collection. The emotional schema therapy was performed for 8 sessions, 90 minutes each for the experimental group, and the control group received none. Multivariate analysis of covariance (MANOVA) and one-way analysis of covariance (ANOVA) on the SPSS software version 23 were used for data analysis. Results: In this study, participants ranged in age from 12 to 18 years old, with a mean of 15.53 years (SD = 1.84). Results suggest that the schema therapy approach had positive effects on aggression and emotion dysregulation in adolescent's girls with self-harm (P-value<0.001). Conclusions: Study results showed that schema therapy for aggression and emotion dysregulation was a cost-benefit intervention for adolescent girls with self-harm aged between 12 and 18.