This study presents an investigation of the effects of peer attitude, gender, and blood alcohol level on driving performance using a driving simulator. The subjects were 18 male and 18 female social drinkers from the general population, aged 18-25, and holding a current drivers' licence. Subjects were randomly assigned to pro or against drinking driving conditions and tested at different blood alcohol levels. The results revealed that subjects in the for drinking driving condition perceived themselves to be more capable than they actually were and drove increasingly faster and made more mistakes than subjects in the against drinking driving condition when under the influence of alcohol. Significant sex differences were observed only for performance on the driving simulator. Males, in the main, engaged in more dangerous driving and risk taking in simulated driving conditions than females.