This data compares effortful and effortless prosocial behavior between older and younger adults. Forty-six older adults (M= 69.57 years; range = 65 -77) and 65 younger adults (M= 27.43 years; range = 20 -34) completed the study on Prolific, an online participant pool. Participants completed the ‘Pay-It-Forward' effortful decision-making task (40 trials) and a version of the Dictator Game, an effortless prosocial decision-making task (20 trials). Subject-level and trial-by-trial data are available for both tasks. Demographics information includes age, gender, race, and income. Participants were compensated $7 for completing the study. Eligibility criteria included age (20 – 35 for younger adults and 65 – 85 for older adults), being English-speaker, and current residing in the United States. After providing digital informed consent, participants completed demographic questionnaires. Then, participants completed the prosocial effortful decision-making task (Pay-It-Forward Task) or the prosocial effortless decision-making task in a counterbalanced order. Participants were told the estimated time that each task would take in advance but were not told exactly how many trials of each task they would complete. Upon completion of the study, participants were compensated 7 US dollars and an additional 1-12 US dollars in monetary bonuses based on their performance on both tasks.