Research has shown that early maturation is related to problematic alcohol use, yet the differential effect of early pubertal timing (i.e., younger age at menarche) on the onset of alcohol use and subsequent level of alcohol use has rarely been examined. This distinction is relevant, as younger age at menarche can have differential effects on these outcomes, which in turn can have long-lasting effects. Therefore, the present study examined the relationship between age at menarche and adolescent alcohol use among girls, hereby distinguishing between onset and level of alcohol use. In addition, the moderating effects of alcohol-specific rules, child disclosure and class gender composition were examined. Participants were 430 girls from a Dutch four-wave survey, with a mean age of 12.17 years (SD = 0.50) at the beginning of the study. Results showed that the probability of onset of alcohol use was increased by younger age at menarche, but only when girls were younger than 15. Moderation analyses showed that younger age at menarche increased the risk of alcohol onset only in low risk girls (with high levels of alcohol-specific rules and in classes with a high percentage of girls). Once adolescent girls started drinking alcohol, younger age at menarche was associated positively with alcohol consumption only for girls in classes with a moderate to high percentage of girls. These findings confirm that younger age at menarche is a risk factor for the onset of alcohol use, but strongly suggest that this effect is strongest for girls having restrictive alcohol-specific rules and in classes with a high percentage of girls. Possibly, in the absence of social factors that "push" to alcohol use, biological factors (like age at menarche) become more important. Another possibility is that adolescent girls start drinking alcohol to oppose their parents if they set too strict alcohol-specific rules.