The view that one ought to do what one has most reason to do has served as a blueprint for a variety of more specific accounts of how reasons determine the deontic status of actions. I suggest a new such account with remarkable explanatory power. Over and above returning the intuitively correct results in a wide range of cases, the suggested account entails important deontic principles, including ones that axiomatise Standard Deontic Logic. These results can be turned into the core of an explanation of deontic principles in terms of facts about how reasons interact in determining oughts.