This study was conducted in the context of an increasing number of reported cases of bullying, school violence, and juvenile crimes in Vietnam. Aggressive behaviors were associated with school violence. The objective of this study was to assess four types of aggression expressed simultaneously by form and function in high school students. A cross-sectional study consisted of 644 high school students in Hanoi and Hung Yen province. Peer Conflict Scale was used. The results showed that 99.4% of students reported aggressive behavior, with 30.4% reporting "often" and 20.8% reporting "always" doing at least one aggressive behavior. Reactive-overt aggression was reported the most. Proactive – overt aggression was reported the least. Unlike many previous studies, female students exhibited a higher level of aggression than male students. Positive correlation was found among 4 types of agreesion. Logistic regression analysis showed that one type of agreesion could predict the others Research findings are useful developing classroom management plans and psychological support for students.