INTRODIJCTIONAre we all likely to behave contrary to our morality or to commit illegal acts? This seems probable if we refer to past studies in social psychology. Milgram's subjects (Milgram, 1974) gave a 'lethal' reinforcement simply when ordered to do so by a 'scientific authority'. The 'guards' in Zimbardo's classic prison study (1 969) readily acted as torturers. However, the majority of criminological approaches to delinquency' (biological, psychological or sociological) are based on the implicit postulate that there are natural differences between delinquent and non-delinquent individuals. In consequence, there is little research on situational influences in the study of delinquency, compared to the attention given to the social and psychological attributes of offenders. As Amdur (1989) notes, natural differences Addressee for correspondence: F. Van Duuren, Univcrsitb Charles de Gaulle, Labacolil, U F R dc Psychologie 59653 Villeneuve-D'Ascq Cedex, France.We would like to thank R. Bialek, P. Gadeyne, A . Mark and L. Norgd who were experimenters, V.Christophe and I. Myatovic who performed the confederate's role and N. Emler for his helpful comments.'This term refers here to offences such as theft, vandalism and fraud, the behaviours which appear daily in newspaper headlines in the petty delinquency column.