This paper looks at deceit’s ambivalent nature in Marguerite de Navarre’s Heptaméron. The first part of the article is made up of an overview of how legal commentators in the fifteenth and sixteenth centuries understood the notion of deceit as both good (dolus bonus) and bad (dolus malus). The second part turns to Marguerite de Navarre’s activities in the fall of 1525, when she was trying to negotiate her brother, Francis I’s freedom from Charles V’s prison following his capture at the Battle of Pavia. The legal commentaries and accounts of Marguerite’s activities point to a decidedly ambivalent understanding of deceit in sixteenth-century France. In many of the Heptam.ron’s novellas, as was the case in these commentaries and accounts, deceit can be good or bad, depending on who is doing it and to what end. Such an understanding of deceit helps modern readers grasp the moral complexity of the Heptaméron.