Research in the retrospective memory domain has shown that individuals encode information less effortfully when expecting a reminder system (i.e., external store) to be available at the test. Critically, this expectation leads to worse memory performance when the reminder is unexpectedly removed. The present study examined whether these findings extend to prospective memory (PM) intentions, which are thought to maintain a privileged status in memory and therefore may be less sensitive to expectancy effects. Participants formed the intention to make a special PM response to target items across four ongoing task blocks. Study duration (Experiments 1 and 3), pupil size (Experiment 2), and self-report (Experiments 1-3) indexed encoding effort while learning these targets. Participants had reminders available across the first three blocks (i.e., targets listed at the top of the screen), but not on the fourth. Critically, only one condition was informed that they would not have a reminder prior to encoding targets in the fourth block. Results showed that expecting a reminder lowered objective (Experiments 1 and 3) and subjective (Experiments 1-3) encoding effort and reduced unaided PM retrieval (Experiments 1-3) in the fourth block, independent of memory load (Experiments 3). Objective (Experiments 1 and 3) and subjective (Experiments 1-3) effort also partially mediated the influence of expectations on unaided PM retrieval. These findings suggest PM and retrospective memory encoding operate similarly and that participants can alter learning to more effectively commit PM targets to memory when reminders are not expected. (PsycInfo Database Record (c) 2025 APA, all rights reserved).