This study examined the contribution of demographic characteristics, early maltreatment, and peer and family relationships during adolescence to the prediction of aggressive and nonaggressive antisocial behavior (AASB and NAASB, respectively) during young adulthood; and determined whether adoption status has additional ability to predict ASB, once background, early experience, peer, and family variables were controlled. Data from adolescent and parent interviews were used from Waves 1 (predictors) and 3 (outcomes) of the National Longitudinal Study of Adolescent Health (Add Health). The sample included 337 adopted and 10,339 nonadopted adolescents whose mean ages were 15.8 at W1 and 21.7 at W3. Although AASB and NAASB were predicted by background characteristics, early maltreatment, peer relations, and family relationships, adoption status had little to no additional predictive power once the other variables were controlled.