This essay seeks to explain a morally important class of psychological incapacity-the class of what Bernard Williams has called ''incapacities of character.'' I argue for two main claims: (1) Caring is the underlying psychological disposition that gives rise to incapacities of character. (2) In competent, rational adults, caring is, in part, a cognitive and deliberative disposition. Caring is a mental state which disposes an agent to believe certain considerations to be good reasons for deliberation and action. And caring is a mental state which structures an agent's practical deliberation, by establishing presumptive boundaries on the landscape of possibilities over which her deliberative imagination ranges. Incapacities of character are a consequence of the structure which these presumptive boundaries give to an agent's deliberation.Bernard Williams has argued that a person may find that she is incapable of doing something, because her character renders it ''unthinkable'' for her. A person's character is revealed not merely by her actions, but by such incapacities, Williams claims. I think that this claim is correct. To the extent that it is, it helps give determinate shape to a large question: what does a person's character consist in? What are the underlying psychological dispositions which constitute a person's character, and how do they manifest themselves in the incapacities Williams identifies? In what follows, I will argue that a person's character is constituted, in