This article studies whether conformism behavior affects individual outcomes in crime. We present a social network model of peer effects with ex ante heterogeneous agents and show how conformism and deterrence affect criminal activities. We then bring the model to the data by using a very detailed data set of adolescent friendship networks. A novel social network-based empirical strategy allows us to identify peer effects for different types of crimes. We find that conformity plays an important role for all crimes, especially for petty crimes. This suggests that, for juvenile crime, an effective policy should be measured not only by the possible crime reduction it implies but also by the group interactions it engenders.