This research examines how school administrators can motivate children to make more healthful food choices using incentives, pledges, and competitions as interventions. A six-month field study was conducted across 55 elementary and middle schools, and the authors analyzed the data using a two-level Bayesian hierarchical linear model. All three interventions increased the choice of fruits and vegetables (the proportion of children choosing additional servings increased 3 to 24 percentage points) ten weeks after the interventions ended. However, younger (Grades 1 and 2) and older (Grades 3–8) children responded differently to the interventions. Although both younger and older children responded more favorably to the competition intervention than to the pledge or incentive interventions, the effects of the competition and incentive interventions were more pronounced among the younger children. A second field study, also with schoolchildren, examined the role of pledge reminders on adherence to the pledge. The presence of a visible reminder of a pledge resulted in significantly better outcomes than no reminder of a pledge.