The purpose of this work is to explicate Thomas Aquinas' teaching regarding the nature of satisfaction, punishment, and the relation between the two in the Passion of Christ. This task is undertaken as a response to recent treatments of Aquinas' soteriology that misinterpret his understanding of the penal nature of Christ's work of satisfaction. I argue that Aquinas' explication of Christ's ‘satisfactory punishment’ on the cross does not reduce the salvific significance of the Passion to the mere endurance of a penalty in order to fulfill an arbitrary legal requirement, nor does it reflect a notion of God as wrathful and delighting in human suffering. Rather, the punishment that constitutes the Passion is a complex reality that is willed by God and chosen by Christ as a fitting means of attaining the end of his saving mission, namely, the healing and elevation of sinners.