A longitudinal, prospective design was used to examine the roles of peer rejection in middlechildhood and antisocial peer involvement in early adolescence in the development of adolescentexternalizing behavior problems. Both early starter and late starter pathways were considered.Classroom sociometric interviews from ages 6 through 9 years, adolescent reports of peers'behavior at age 13 years, and parent, teacher, and adolescent self-reports of externalizing behaviorproblems from age 5 through 14 years were available for 400 adolescents. Results indicate thatexperiencing peer rejection in elementary school and greater involvement with antisocial peers inearly adolescence are correlated but that these peer relationship experiences may represent twodifferent pathways to adolescent externalizing behavior problems. Peer rejection experiences, butnot involvement with antisocial peers, predict later externalizing behavior problems whencontrolling for stability in externalizing behavior. Externalizing problems were most commonwhen rejection was experienced repeatedly. Early externalizing problems did not appear tomoderate the relation between peer rejection and later problem behavior. Discussion highlightsmultiple pathways connecting externalizing behavior problems from early childhood throughadolescence with peer relationship experiences in middle childhood and early adolescence.