David Shoemaker presents a new pluralistic theory of responsibility, based on the idea of quality of will. His approach is motivated by our ambivalence to real-life cases of marginal agency, such as those caused by clinical depression, dementia, scrupulosity, psychopathy, autism, intellectual disability, and poor formative circumstances. Our ambivalent responses suggest that such agents are responsible in some ways but not others. Shoemaker develops a theory to account for our ambivalence, via close examination of several categories of pan-cultural emotional responsibility responses (sentiments) and their appropriateness conditions. The result is three distinct types of responsibility, each with its own set of required capacities: attributability, answerability, and accountability. Attributability is about the having and expressing of various traits of character, and it is the target of a range of aretaic sentiments and emotional practices organized around disdain and admiration. Answerability is about one’s capacity to govern one’s actions and attitudes by one’s evaluative judgments about the worth of various practical reasons, and it is the target of a range of sentiments and emotional practices organized around regret and pride. Accountability is about one’s ability to regard others, both evaluatively and emotionally, and it is the target of a range of sentiments and emotional practices organized around anger and gratitude. In Part One of the book, this tripartite theory is developed and defended. In Part Two of the book, the tripartite theory’s predictions about specific marginal cases are tested, once certain empirical details about the nature of those agents have been filled in and discussed.