The authors conducted a field experiment in 31 primary schools in England & Wales to test the efficacy of different incentives to encourage healthy eating by schoolchildren (n=664). Children’s consumption patterns were monitored for 6 weeks and an intervention was carried out in 2/3rds of the schools for 4 weeks. Children who ate a portion of fruit & veg were rewarded with stickers and small gifts. At the end of the week the stickers could be exchanged for stationery or small toys. There were two incentive programs; (i) piece rate incentives where kids got an extra reward for choosing more than 4 pieces of fruit & veg and (ii) competitive incentives where kids got an extra reward if they received more stickers than their peers.The authors monitored consumption one week before the 4 week intervention, during the intervention itself, one week after and 6 months later.There were two main results. First, the incentives have heterogenous effects, particularly by age and gender. Younger kids and girls are more responsive to competitive incentives, which are more effective overall. Piece rate incentives worked adversely on younger kids. Secondly, most of the effects were short-lived and did not persist once the incentives are removed. An important exception is that those kids from lower SES backgrounds do benefit from longterm effects, remaining 16% more likely to try fruit & veg after 6 months.