We hypothesized that hyperactivity defines the first stage and that antisocial problems definea second stage in a progression that leads eventually to early-onset delinquency. As expected, astructural equation model (SEM) showed that a latent construct for hyperactivity wassignificantly related to a latent construct for antisocial problems. We hypothesized that this pathreflected a shared mechanism, disrupted parental discipline. A second SEM showed that therelation between hyperactivity and antisocial behavior really reflected a shared disruption inparental discipline. A third SEM showed that having antisocial parents was uniquely correlatedwith antisocial children but not with hyperactivity. A fourth SEM showed that early-onsetdelinquency was predicted by a latent construct for antisocial child; but when this was partialedout, the contribution for hyperactivity was nonsignificant.