Implementation intentions are a self-regulatory strategy broadly studied in the area of social cognition that can improve realization of one’s goals and improve performance on prospective memory tasks. Three experiments, using a non-focal task for which the prospective memory targets were specified at the time of intention formation, investigated whether (and how) implementation intentions can improve non-focal prospective memory performance. An improvement in prospective memory performance was accompanied by an increase in the allocation of conscious resources to the prospective memory task, but not by an increase in perceived importance of the prospective memory task. The third experiment also investigated the effects of implementation intentions on recall of the appropriate action and found that accurate action recall was improved by implementation intentions. Finally, the effect of implementation intention instructions on cognitive processes that underlie non-focal prospective memory performance was investigated using a multinomial model.