The degree of continuity and distinctiveness in social competence and antisocial behavior was examined in a longitudinal structural equation model. Participants were 391 typically developing Norwegian middle school students (51% boys), their parents, and teachers and were assessed when they were approximately 13 years of age (a school cohort in 8th grade) and again 17 months later, when they were about 15 years old (in 10th grade). Social competence showed considerable stability across middle school, more than did antisocial behavior. Low social competence at age 13 predicted antisocial behavior at age 15, over and above the variance explained by the earlier assessment of antisocial behavior. While social competence and antisocial behavior both showed a relatively strong negative association concurrently and demonstrated considerable overlap, results suggested that the two constructs should be considered separate dimensions. Findings are presented within a transactional framework and implications for prevention efforts and directions for future research are discussed.