BACKGROUND:Many studies have reported that the earlier the age at first drink (AFDrink) the higher the later drinking levels and related problems. However, unless adolescents proceed into drunkenness, it is unclear why consuming small quantities at early age should lead to later problems. This study investigates the link between AFDrink and problem behaviors (smoking, cannabis use, injuries, fights, and low academic performance) among 15-year-olds who did and did not proceed into drunkenness. Among those with drunkenness experience, we tested whether AFDrink predicted problem behaviors over and above the age at first drunkenness (AFDrunk). METHODS:Multilevel structural equation models were estimated based on a sample of 44,801 alcohol-experienced 15-year-olds from 38 North American and European countries and regions who participated in the Health Behaviour in School-aged Children cross-national survey. RESULTS:Overall, there was a significant association between AFDrink and all 5 problem behaviors. However, this was the case only among those with drunkenness experiences but not among those never drunk. Among the former, AFDrunk was a strong predictor for all 5 problem behaviors, but time from first drink to first drunk did not predict problem behaviors. CONCLUSIONS:Not early alcohol initiation but early drunkenness was a risk factor for various adolescent problem behaviors at the age of 15, that is, there was not consistent relationship for the time before the first drunkenness (i.e., since first drinking). Besides targeting early drinking, particular efforts are needed to impede early drunkenness to prevent associated harm in adolescence and beyond.