Building Better Beings presents a new theory of moral responsibility. Beginning with a discussion of ordinary convictions about responsibility and free will and their implications for a philosophical theory, Manuel Vargas argues that no theory can do justice to all the things we want from a theory of free will and moral responsibility. He goes on to show how we can nevertheless justify our responsibility practices and provide a normatively and naturalistically adequate account of of responsible agency, blame, and desert. Three ideas are central to Vargas' account: the agency cultivation model, circumstantialism about powers, and revisionism about responsibility and free will. On Vargas' account, responsibility norms and practices are justified by their effects. In particular, the agency cultivation model holds that responsibility practices help mold us into creatures that respond to moral considerations. Moreover, the abilities that matter for responsibility and free will are not metaphysically prior features of agents in isolation from social contexts. Instead, they are functions of both agents and their normatively structured contexts. This is the idea of circumstantialism about the powers required for responsibility. Third, Vargas argues that an adequate theory of responsibility will be revisionist, or at odds with important strands of ordinary convictions about free will and moral responsibility. Building Better Beings provides a compelling and state-of-the-art defense of moral responsibility in the face of growing philosophical and scientific skepticism about free will and moral responsibility.