Objective: Young people who are victims of, or witnesses to, aggression are at increased risk of developing a psychological disorder and behaving aggressively themselves. The aim of this study was to report the prevalence of exposure to aggression in a sample of 1 770 students, aged 15–26 years recruited from technical colleges in Thailand. Method: Self-report questionnaires were used to assess the prevalence rates for both experiencing aggression as a victim and for witnessing an aggressive incident. Logistic regression methods were then used to examine the possible association between acting aggressively and being a victim of, or a witness to, aggression. Results: In the previous six months, over half of all students reported being yelled at and had witnessed friends being hit. Those students who reported ‘being pushed’ or ‘being hit’ themselves had higher levels of anger expression. Being an indirect victim and witnessing aggression were only weakly associated with anger expression. Conclusions: Adolescents in Thailand experience high rates of victimisation and commonly witness aggression. Being personally victimised was shown to be significantly related to a subsequent expression of anger, suggesting that interventions to prevent direct confrontation may help to reduce the likelihood of victims becoming perpetrators.