Many European countries have raised the minimum legal drinking age (MLDA) from 16 to 18 over the past decades. These policies often comprise a bundle of reforms including restrictions on alcohol sales to minors, venue access limitations, and advertising controls. We provide novel evidence of the impact of MLDA changes on educational outcomes by exploiting their staggered timing across Spanish regions. Alcohol consumption among adolescents aged 14-17 decreased by 7 to 17% and exam performance improved by 4% of a standard deviation. We also observe a 10% decrease in the use of anxiolytics and hypnosedatives, suggesting improved mental health. There are no significant changes in the use of other substances, leisure habits or study effort. These findings are consistent with neurobiological evidence that alcohol directly impairs cognitive development and increases anxiety-related behaviours. Reducing teenage alcohol consumption represents a substantial opportunity to improve educational outcomes in Europe, where youth drinking rates remain notably high.