While previous research has suggested that prospective memory may be enhanced by providing a social motive (i.e., social importance) or by promising a monetary reward for successful performance, to the best of our knowledge, the underlying mechanisms responsible for these effects are still largely unexplored. In a sample of 96 younger adults, this study investigated how social importance and promising a monetary reward influence the prospective component and the retrospective component of event-based prospective memory separately, with the application of a multinomial modeling approach. Results revealed enhanced prospective memory performance for all importance conditions compared to a standard condition. This improvement was characterized by an increased allocation of resource-demanding attentional processes in performing the prospective memory task at the expense of the ongoing task without an increase in the perceived importance of the prospective memory task. The model-based analyses showed that the beneficial effects of importance arise from an increased engagement of the prospective component, leaving the estimates for the retrospective component unaffected.