The aim of this study was to investigate the mediating role of mentalization ability in the relationship between attachment security and adolescent emotional dysregulation. The present research was a descriptive correlational study. The statistical population of this study was male and female students who were in the age range of 11 to 17 years, who in 2020 were studying in regions one and two of Zanjan City. 200 people were selected using available sampling for this study. The research instruments included the experiences of close relationships questionnaire - (ECR-RS)  (Fraley et al., 2000), Reflective Function Questionnaire for Youth- (RFQ-Y) (Ha & et al., 2013), and Difficulties in Emotion Regulation Scale- (DERS) (Gratz & Roemer, 2004). Data were analyzed using the Pearson correlation test and path analysis. Fit indicators showed an excellent fit of the data with the modified model. Avoidance attachment to the father was directly able to predict emotional dysregulation in adolescents (p<0.001). Also, avoidant attachment to the father and anxious attachment to the mother indirectly and through the ability to mentalize were able to predict emotional dysregulation in adolescents (p<0.001). From the above results, it can be concluded that attachment security and the ability to mentalize together can play a major role in predicting emotional dysregulation in adolescents and it is necessary to pay attention to these factors in emotional regulation promotion programs.