Since 2000, adolescent alcohol use has declined substantially in many high-income countries, particularly in Northern Europe. This study examined whether birth cohorts in Norway who experienced different levels of alcohol consumption in mid-adolescence differed in drinking behaviour when they reached young adulthood. We analysed data from annual population surveys in Norway (2012–2021). The analytic sample comprised data from respondents aged 20–29 years (N = 5266), and we applied four birth cohorts (i.e., 1983–1987, 1988–1992, 1993–1996 and 1997–2001). We applied age categories with two- and five-year intervals and tested whether drinking frequency, heavy episodic drinking (HED) and usual number of drinks per drinking occasion during the past 12 months differed by birth cohort in age-specific strata. Possible cohort differences within age groups were tested using Pearson’s Chi square. There were no statistically significant differences between cohorts with respect to drinking frequency or HED frequency. However, the youngest cohort had fewer drinks per occasion when in their early 20s compared to older cohorts. This study showed that birth cohorts who differed substantially in levels of alcohol consumption in mid-adolescence, only to a little extent differed in drinking behaviour in young adulthood.