This paper reports research into the determinants of four cancer-related risk behaviours: smoking, excessive alcohol consumption, high fat consumption and exposure to artificial sunlight. The results indicate that the four types of risk behaviour are determined by several factors: the perceived behaviour of the social environment, individual's attitudes towards the risk behaviour and self-efficacy perceptions on changing the risk behaviour. High fat consumption differs from the other risk behaviours in that people tend not to be aware of their high fat consumption. No significant relationships were found among the risk behaviours apart from small correlations between smoking and heavy alcohol consumption, and between high fat consumption and heavy alcohol consumption. The implications of these results for the development of behaviour change programs are discussed.