Prospective memory (PM) is the ability to perform a planned action at a future time. Older adults have shown moderate declines in PM, which are thought to be driven by age-related changes in the prefrontal cortex. However, an age-PM paradox is often reported, whereby deficits are evident in laboratory-based PM tasks, but not naturalistic PM tasks. The key aims of this study were to: (1) examine the age-PM paradox using the same sample across laboratory and ecological settings; and (2) determine whether self-reported PM and cognitive factors such as working memory and IQ are associated PM performance. Two PM tasks were administered (ecological vs. laboratory) to a sample of 23 community-dwelling older adults (Mage = 72.30, SDage = 5.62) and 28 young adults (Mage = 20.18, SDage = 3.30). Participants also completed measures of general cognitive function, working memory, IQ, and self-reported memory. Our results did not support the existence of the age-PM paradox. Strong age effects across both laboratory and ecological PM tasks were observed in which older adults consistently performed worse on the PM tasks than young adults. In addition, PM performance was significantly associated with self-reported PM measures in young adults. For older adults, IQ was associated with time-based PM. These findings suggest that the age-PM paradox is more complex than first thought and there are differential predictors of PM performance for younger and older adults.