The aim of the current study was twofold: (1) to investigate the concurrent and longitudinal links in 3–5-year old children between the antisocial and prosocial tendencies of the children's nominated best friends and children's own antisocial and prosocial behavior; and (2) to investigate age and gender as possible moderators of these links. As hypothesized, the study found that children's level of antisocial and prosocial behavior was significantly related to the levels of antisocial and prosocial behavior demonstrated by their nominated best friends.