This study investigated the relationship between combat exposure and adult antisocial behavior in a sample of 2,490 male Army veterans of the Vietnam War who completed questionnaires about their psychological functioning. After adjustment for history of childhood behavior problems, posttraumatic stress disorder diagnosis, and demographic and military characteristics, it was found that veterans who experienced high and very high levels of combat were twice as likely to report adult antisocial behavior as veterans with no or low levels of combat and were also more likely to meet criteria for antisocial personality disorder. The results indicate that exposure to traumatic events during late adolescence or early adulthood is associated with multiple adult adjustment problems in vocational, interpersonal, and societal functioning. Treatment focusing on the effects of the trauma is likely to be necessary but not sufficient for improving affected veterans' behavior.