Prospective memory (PM), the ability to remember an intention in the future, is essential to children's everyday lives. We explored age differences (6- to 7- vs. 10- to 11-year-olds) in PM depending on the nature of the task and the children's motivation. Children performed event-based PM tasks (in which the cue was presented during the ongoing activity) and activity-based PM tasks (in which the cue consisted of finishing the ongoing activity). Additionally, the children were assigned to either a reward condition or a no-reward condition. The results showed better performance in event than in activity based tasks, with older children outperforming younger children in both. There was a marginal effect of reward for PM accuracy. These patterns suggest that the cue detection process and children's motivation play a role in PM performance during development.