The importance of peer 'pressure' as a major causal factor in the onset of illicit drug use is reviewed. Most of the data adduced in support of this hypothesis are associational and therefore no basis for the inference of causality. While there is evidence to show that peer factors are associated with illicit drug use this evidence has, in many cases, been inappropriately interpreted or cited as support for peer pressure when it should have been more appropriately interpreted as evidence for peer preference. The operational definition of peer pressure or peer influence in many research reports is such that it is clear the researchers were only addressing one factor, amongst others, in a dynamic and reciprocal relationship between individuals and peers. There is a need to reassert the role of the individual in their own development, with a particular need to reassert the role of choice and motivation in relation to drug use and social interaction with peers, without assuming that motivation for drug use arises solely out of personal or social inadequacy. Some implications for educational interventions and health promotion are discussed.