Stephen Darwall presents a series of essays that explore the view that central moral concepts are irreducibly second-personal, in that they entail mutual accountability and the authority to address demands. He illustrates the power of the second-personal framework to illuminate a wide variety of issues in moral, political, and legal philosophy. Section I concerns morality: its distinctiveness among normative concepts; the metaethics of 'bipolar obligations' (owed to someone); the relation between moral obligation's form and the substance of our obligations; whether the fact that an action is wrong is itself a reason against action (as opposed to simply entailing that sufficient moral reasons independently exist); and whether morality requires general principles or might be irreducibly particularistic. Section II consists of two essays on autonomy: one discussing the relation between Kant's 'autonomy of the will' and the right to autonomy, and another arguing that what makes an agent's