The current dissertation applied a modified version of the Theory of Planned Behaviour (TPB) to predict reactive physical aggression between university students. In addition to examining the primary constructs of the traditional TPB model (attitudes, subjective norms, perceived behavioural control and intentions), this dissertation extended the traditional model by also examining the impact of implicit attitudes toward aggression as well as executive functioning in the prediction of reactive physical aggression. Results provided support for the application of the traditional TPB model in the prediction of reactive physical aggression, although implicit attitudes and executive functioning did not significantly contribute to the prediction of aggressive behaviour in this sample. Gaining a better understanding of the predictors of reactive physical aggression between university students may lead to the identification of early intervention strategies for individual aggressors. This may in turn help to prevent the possible escalation of aggressive behaviour and create a safer and less threatening campus environment for all students.