Obesity rates have doubled in the last forty years, and a major cause is the consumption of sugar-sweetened beverages. In this paper, we identify channels through which information – about health benefits or taste – affects beverage choice. We conduct a field experiment in a school lunchroom with 2,500 children, evaluating the impact of informational prompts on beverage choice and consumption over 2 weeks. We find that prompts alone increase the proportion of children choosing and consuming the healthier white milk relative to sugar-sweetened chocolate milk from 20% in the control group to 30% in the treatment groups. Adding health or taste messaging to the prompt does not seem to make a difference. We survey students and find that most prompts affect perceived healthfulness of the milk, but not perceived taste. Finally, we find that the prompts are nearly as effective as a small non-monetary incentive.