As one of the three sources of the moral act in Aquinas’s philosophy, intention is fundamental to the understanding of his ethics. And while intention’spsychological and linguistic dimensions have been appreciated recently, after the appearance of Anscombe’s Intention, the Aristotelian physical framework ofAquinas’s thought on the issue has been neglected. Taking only the end of the agent into account in intentional analysis has led to incorrect interpretations of moral action, particularly among new natural law theorists. In this paper, I propose (...) an understanding of intentio and praeter intentionem in Aquinas that elucidates his distinctions regarding justified killing, as well the bearing of intention in intentional action and moral acts. (shrink)