In four studies, we investigated the role of remembering, reflecting on, and mutating personal past moral transgressions to learn from those moral mistakes and to form intentions for moral improvement. Participants reported having ruminated on their past wrongdoings, particularly their more severe transgressions, and they reported having frequently thought about morally better ways in which they could have acted instead (i.e., morally upward counterfactuals; Studies 1–3). The more that participants reported having mentally simulated morally better ways in which they could have acted, the stronger their intentions were to improve in the future (Studies 2 and 3). Implementing an experimental manipulation, we then found that making accessible a morally upward counterfactual after committing a moral transgression strengthened reported intentions for moral improvement—relative to resimulating the remembered event and considering morally worse ways in which they could have acted instead (Study 4). We discuss the implications of these results for competing theoretical views on the relationship between memory and morality and for functional theories of counterfactual thinking.