The effects of interrupting an event-based prospective memory (PM) task and its associated ongoing task were compared for two groups of children: 8- to 9-year-olds (n = 35) and 12- to 13-year-olds (n = 28). Additionally, PM performance was examined as a function of attainment on a battery of tests of executive functioning (viz., Controlled Oral Word Association Test, Letter Number Sequencing Test, Stroop Color and Word Test, and Trail Making Test). A significant main effect of age indicated that the older children correctly carried out intended actions more often than the younger children. Consistent with the prefrontal model of PM, interruption had no impact on PM accuracy in the older group but produced reliable decrements to the accuracy of the younger group. Whereas IQ showed no association with PM performance, reliable relations between PM skills and aspects of their executive functioning were found.