We often explain human actions by reference to the desires of the person whose actions we are explaining: “Jane is studying law because she wants to become a judge.” But how do desires explain actions? A widely accepted view is that desires are dispositional states that are manifested in behavior. Accordingly, desires explain actions as ordinary physical dispositions, such as fragility or conductivity, explain their manifestations, namely causally. This paper argues that desires, unlike ordinary physical dispositions, are “manifestation-dependent dispositions”: dispositions whose attribution depends on their having been manifested. This feature of desires, I suggest, favours a “context-placing” approach to understanding how desires explain actions.