The goal of this study was to investigate the extent to which aggressive-disruptive peers contribute to the development of externalizing and internalizing problems in children, while controlling for children's own behavior. We examined 2 sets of peers: (1) those that the child nominated as friends, and (2) those that nominated the child as a friend. The participants were 236 boys and girls attending 3rd to 5th grade at the beginning of the study, who were followed over a period of 2 years. Results showed that choosing more aggressive peers on the nomination procedure was associated with more externalizing problems and self-reported depressive symptomatology over time. On the other hand, being liked by more aggressive children generally was not associated with elevated externalizing or internalizing problems.