The role of deviant peers in adolescent antisocial behavior has been well documented, but less is known about individual differences in susceptibility to negative peer influence. This study examined whether specific temperament dimensions moderate the prospective relationship between peer deviance and delinquent behavior in early adolescence. Participants included 704 adolescents recruited from the community. At baseline, parents provided information on adolescents' temperament and youth reported on their own and their friends' delinquent behavior. Selfreports of adolescents' delinquent behavior were collected again 16 months later. Peer deviance was related to delinquent behavior over time more strongly for adolescents with low levels of task orientation, flexibility, and positive mood, compared to youth with high levels of task orientation, flexibility, and positive mood. Analyses of gender differences indicated that low flexibility increased susceptibility to negative peer influence only for males, but not females. General activity level and sleep rhythmicity did not moderate the effect of peer behavior on delinquency.