Four experiments demonstrated that recalling memories from one's own childhood lead people to experience feelings of moral purity and to behave prosocially. In Experiment 1, participants instructed to recall memories from their childhood were more likely to help the experimenter with a supplementary task than were participants in a control condition, and this effect was mediated by self-reported feelings of moral purity. In Experiment 2, the same manipulation increased the amount of money participants donated to a good cause, and self-reported feelings of moral purity mediated this relationship. In Experiment 3, participants who recalled childhood memories judged the ethically-questionable behavior of others more harshly, suggesting that childhood memories lead to altruistic punishment. Finally, in Experiment 4, compared to a control condition, both positively-valenced and negatively-valenced childhood memories led to higher empathic concern for a person in need, which, in turn increased intentions to help.