The relation between social rejection and growth in antisocial behavior was investigated. In Study 1, 259 boys and girls (34% African American) were followed from Grades 1 to 3 (ages 6–8 years) to Grades 5 to 7 (ages 10–12 years). Early peer rejection predicted growth in aggression. In Study 2, 585 boys and girls (16% African American) were followed from kindergarten to Grade 3 (ages 5–8 years), and findings were replicated. Furthermore, early aggression moderated the effect of rejection, such that rejection exacerbated antisocial development only among children initially disposed toward aggression. In Study 3, social information-processing patterns measured in Study 1 were found to mediate partially the effect of early rejection on later aggression. In Study 4, processing patterns measured in Study 2 replicated the mediation effect. Findings are integrated into a recursive model of antisocial development.