The goal of the present study was to examine the role of executive functions in age-related differences in prospective memory. Therefore, in a sample of 40 young ( M=24.8; SD=2.0) and 40 old adults ( M=69.3; SD=5.6), event- and time-based prospective memory as well as five executive functions were assessed. Results show that age differences in prospective memory performance depend largely on age-related individual differences in executive functions. Furthermore, the results indicate several executive functions to differentially predict prospective memory performance. The event-based prospective memory task requires inhibition to avoid distraction from irrelevant items. The time-based prospective memory task requires the flexible shifting of cognitive sets. Overall, the data support the assumption that age differences in prospective memory performance are closely related to executive functioning. In addition, time- and event-based prospective memory seem to rely on different executive processes.