This title was first published in 2002: This book is an analysis of the ways in which mental states ground attributions of responsibility to persons. Particular features of the book include: attention to the agent's epistemic capacity for beliefs about the foreseeable consequences of actions and omissions; attention to the essential role of emotions in prudential and moral reasoning; a conception of personal identity that can justify holding persons responsible at later times for actions performed at earlier times; an emphasis on neurobiology as the science that should inform our thinking about free will and responsibility; and the melding of literature on free will and responsibility in contemporary analytic philosophy with legal cases, abnormal psychology, neurology and psychiatry, which offers a richer texture to the general debate on the relevant issues.