This thesis is an investigation of a novel application of the Theory of Planned Behaviour (TPB), examined in order to elucidate social-cognitive factors underlying self-harm among university students. The utility of TPB components (attitudes, subjective norms, perceived behavioural control) and the role of identification with self-harm were examined as predictors of self-harm intent. Social-cognitive variables, namely, self-efficacy, perceived controllability, and identification, predicted intent over and above clinical variables (i.e., depressive, anxiety, dissociative symptoms). Furthermore, instrumental attitudes and self-efficacy mediated the relation between clinical variables and future intent. Finally, identification with self-harm was found to moderate the relation between injunctive norms (i.e., what peers think about self-harm) and intent. The clinical and conceptual implications of these findings and future directions will be discussed.