Desires lead to actions, influence feelings, and determine what counts as a reward. Recent empirical evidence shows that these three aspects of desire stem from a common biological origin. Informed by contemporary science as much as by the philosophical tradition, Three Faces of Desire reveals this common foundation and builds a striking new philosophical theory of desire that puts desire's neglected face--reward--at its core. Schroeder delves into the way that actions and feelings are produced in the brain, arguing that a distinctive system is responsible for promoting action, on the one hand, and causing feelings of pleasure and displeasure, on the other. This system, the brain's reward system, is the causal origin of both action and feeling, and is the key to understanding the nature of desire.