Medieval theologians considered that it was a mortal sin to act against one’s conscience, even though they knew that conscience sometimes erred. This article inquires how they, as pastors, nevertheless engaged with the laity’s real-world experiences of conscience and with problems that this involved. In focus of the inquiry are pastoral tracts written by Jean Gerson (d. 1429). In these tracts, Gerson described troubling behaviour that he associated with malfunctions of conscience, and he observed how the precept that conscience obliged was a burden that some individuals could not handle. Gerson offered an analysis of these problems as well as alleviating pastoral advice. He agreed that one should obey one’s conscience, but this article argues that his analysis and advice went far towards circumscribing the force of this precept.