The current thesis project focuses on the role of metacognition in prospective memory (PM). Study 1 examined whether young and older adults differ in their metacognitive awareness of their PM performance and if their predictions are related to performance in a laboratory task. Study 2 examined whether predictions differ between the laboratory and naturalistic settings. Study 3 examined age differences in metacognitive awareness of PM performance in and outside the laboratory within the same sample of young and older adults. Results revealed the expected pattern of performance found in the Age PM Paradox: an age benefit in the naturalistic task. Regarding the predictions young adults showed a general pattern of underconfidence in the laboratory contrasted with great overconfidence outside of the laboratory. Whereas older adults demonstrated overall better metacognitive awareness. The present thesis suggests metacognition as a key factor in explaining age differences in the Age PM Paradox.