The theory of planned behaviour was used to examine academic dishonesty among secondary school students in Hong Kong. Participants were 386 students in Forms 1-3 (Grades 7-9). Attitudes toward cheating, perceived behavioural control, and moral obligation were positively related to the intention to cheat, but only the subjective norm against cheating was significantly related to self-reported cheating behaviour. The subjective norm was both a predictor of self-reported cheating and a moderator of the relationship between the intention to cheat and self-reported cheating: the intention predicted the behaviour only when the subjective norm against cheating was perceived to be weak.