Reducing meat and fish consumption in wealthier countries would help mitigate climate change, raising the question of the most effective ways to achieve this. Price influences the food people buy, but to our knowledge no published field study has assessed the impact on sales of experimentally altering the price of meat and vegetarian meal options. We ran an experiment across 106 mealtimes with 13,840 meal selections at a college cafeteria in the University of Cambridge (UK), introducing a small change to the price of vegetarian meals (decreased by 20p from £2.05 to £1.85) and meat meals (increased by 20p from £2.52 to £2.72). Total meal sales did not differ significantly before and after the price change. When controlling for other variables, changing price significantly increased the proportion of vegetarian sales by 3.2 percentage points (p=0.036). However, there was no significant change in meat sales before and after the price change, although fish sales did decline by 2.8 percentage points (p=0.010). When analysed by individual diners’ pre-experimental meal choices (N=325), the price intervention significantly affected only the quartile of diners with the highest prior rates of vegetarian and vegan meal selection (“MostVeg" quartile), who increased their vegetarian meal selection by 13.7 percentage points (p=0.011). Students mainly pay for meals on their university cards and rarely pay with cash, which may lessen the impact of a price intervention in this context. Our results suggest price changes may be one lever for increasing vegetarian meal consumption. Further field studies are needed to test different price changes, and in non-university populations