Background: The school context is associated with adolescent alcohol use, but it is not clear whether this association continues into adulthood. This study examined whether exposure to drunkenness oriented drinking culture in 9th grade school class is associated with individuals' heavy episodic drinking (HED) from adolescence to midlife. Methods: Participants in the 'Northern Swedish Cohort' study aged 16 years in 1981 were followed-up when aged 18, 21, 30 and 43 (N = 1080). Individual-level factors were HED, positive attitudes towards drunkenness, early initiation of HED and peer-oriented spare-time. School class-level drinking culture was measured as classmate reported HED, positive attitudes, early initiation of HED and peer-oriented spare time. Multilevel log-binomial regression analyses were adjusted for gender, parental socioeconomic background, family structure and HED at age 16. Results:After adjustment for sociodemographic factors several cross-sectional and longitudinal associations were found between class-level indicators of drinking culture and individual HED. After additional adjustment for age 16 HED, most associations attenuated. The risk ratio (95% confidence interval) for engaging in HED at age 43 was 1.58 (1.03-2.42) times higher for those who at age 16 had many classmates reporting positive attitude towards drunkenness. Conclusions: These findings suggest that drinking culture in school may have a long-lasting impact on drinking habits in adulthood. The associations with HED at follow-ups are likely mediated by HED in adolescence. Studies on alcohol use would benefit from taking into account both individual and contextual factors in a life course perspective.