A 10-item self-report scale for mild social deviance (the Social Motivation Questionnaire) was developed and used in a study examining the role of social deviance in traffic accident risk. The scale focused on self-serving behaviours which might directly or indirectly harm the interests of others. Data were obtained from 108 drivers taking part in a research programme examining a range of factors underlying traffic accident risk. Apart from social deviance scores, measures were taken of Type-A behaviour pattern, decision-making style, self-reported driving style, age, sex, annual mileage, and accidents over a three-year period. The results indicated that the social deviance scale yielded a good spread of values and had adequate intra-scale reliability. Social deviance was positively correlated with accident rates independently of age, sex and annual mileage. The association between social deviance and accident rates appeared to be partly mediated by faster driving speed. The results indicate that, even within the general population, social deviance can show measurable variation and that this variation is predictive of traffic accident risk.