BACKGROUND: Prevention programs often aim at preventing early onset of drinking (EOD) on the grounds that this may curb heavy drinking in adulthood. While many studies have shown an association between EOD and adult alcohol use disorders, these findings could be inflated by retrospective reports or insufficient control for confounders. This study examined the association between EOD behavior assessed in early adolescence and heavy drinking in adulthood, controlling for deviant behavior and parental heavy drinking. METHODS: Data were collected prospectively over a 13-year period from 1,311 Norwegian school students. At t1 (ages 13 to 14 years), onset of drinking behavior (any drinking and heavy episodic drinking), conduct problems (CP), other problem behaviors, and parental heavy drinking were assessed. At t2 (ages 26 to 27 years), heavy drinking behavior was assessed in terms of heavy episodic drinking frequency and AUDIT score. RESULTS: EOD behavior was associated with CP, other problem behaviors, and parental heavy drinking in early adolescence. A higher risk of heavy drinking in adulthood was found among those with EOD behavior, yet after control for CP, this association became small and statistically nonsignificant. Among low-risk individuals (i.e., those with no CP at t1), there was no association between EOD behavior and heavy drinking in adulthood, while there was a significant association among those with CP. CONCLUSIONS: EOD behavior appears not per se responsible for heavy drinking in adulthood unless being part of a broader array of problem behaviors.