Accurate descriptions of sex differences in the development of childhood conduct problems and adolescent delinquency will inform theories of their causes in fundamentally important ways. Using data on 4,572 offspring of a national sample of women, we tested descriptive hypotheses regarding sex differences. As predicted, the magnitude of sex differences varied with age, suggesting that multiple processes differentially influence levels of these behaviors in females and males across development. During childhood, boys scored lower on measures of cognitive ability and exhibited lower sociability and compliance and greater hyperactivity, oppositional behavior, and conduct problems. Most of these variables were associated with childhood conduct problems and adolescent delinquency equally in females and males, but maternal delinquency and early childhood sociability were correlated more strongly with childhood conduct problems in males and childhood compliance predicted adolescent delinquency more strongly in females. Both sexes exhibited both childhood-onset and adolescent-onset trajectories of delinquency. Although more males followed a childhood-onset trajectory, there were few sex differences in the early childhood risk correlates of either delinquency trajectory.
