In this research paper, we have studied the intermediary role of difficulties in emotion regulation in the relation between parents' emotional availability and reactive-proactive aggression in adolescents. The study has been carried out with 776 high school students (423 girls, 353 boys). Their age ranges from 14 to 19, and the age average is 16.38 (Ss=1.13). The data, in this study, have been collected by using "Reactive - Proactive Aggression Scale", "Parents' Emotional Availability Scale" and "Difficulties in Emotion Regulation Scale". The collected data was analysed through correlation analysis while regression analysis was used for the mediator effect and bootstrap analysis for the significance of indirect effect test. The findings of the study suggest that the reactive-proactive aggression has a positively meaningful relation with difficulties in emotion regulation, but it has a negatively meaningful relation with parents' emotional availability. According to the results of correlation and regression-based bootstrapping method, it has been determined that the difficulties in emotion regulation have a partial mediating role in the relation between parents' emotional availability and reactive-proactive aggression. We believe that the data collected during this study can be valuable sources for further studies and used for reducing the incidence of aggressive behaviours of adolescents particularly at schools.