Although there is widespread agreement about the need to reduce teenagers’ consumption of sugar-sweetened beverages, banning these drinks from the school environment is not always feasible. In this paper, we tested whether increasing the assortment of healthier alternatives and clearly labelling them as healthy by means of traffic light coding qualifies as an alternative approach to reduce the consumption of sugar-sweetened beverages at school. In a field study, we tripled the assortment of healthy (‘green’) and relatively healthy (‘amber’) drinks and kept the assortment of sugar-sweetened (‘red’) drinks constant during five intervention weeks in two treatment Belgian schools. Compared to baseline and to an untreated control school, we found that the relative market share of red beverages dropped by more than 30 percentage points. In one school, this market share was taken by both green and amber drinks, while in the other school, only the consumption of amber drinks increased. We suggest that this easily applicable intervention circumvents some of the friction that accompanies banning sugar-sweetened drinks.