Background: The age-prospective memory-paradox describes the general pattern of age-related deficits in laboratory-based prospective memory tasks and age-related benefits in naturalistic tasks that are carried out in participants' everyday lives. However, the mechanisms which are critical in determining the direction of age effects remain poorly delineated. Method: Twenty young and 20 old adults performed a laboratory and a naturalistic prospective memory task, which were similar in structure and demand. Several factors highlighted in recent theoretical models as potentially important to understanding the paradox (motivation, metacognitive awareness, activity absorption, control over the task) were assessed and their contribution to the age paradox empirically explored. Results: First, analyzing mean level age differences, the paradox was confirmed. Second, exploring possible correlates of the paradox revealed that, while low levels of daily activity absorption, high motivation and good metacognitive awareness were associated with age benefits in prospective memory performance in the naturalistic task, high ongoing activity absorption and low control over the prospective memory cue seem important for understanding age deficits in lab-based tasks. Conclusion: The current study confirms the age-prospective memory-paradox within one sample and with carefully matched laboratory and naturalistic tasks. Additionally, it takes an important step forward in clarifying the role of different factors in understanding age effects across these different contexts. The results indicate that the relative importance of different factors vary as a function of assessment context, with conceptual as well as applied implications.