autonomy principally in tenns of the agent's conscious choice of ends or conduct. From this, the cognitivist emphasis on mental states and their contents naturally follows. The presence of specified mental states, as signifying agent choice, thus becomes the hallmark of responsible conduct. Capacities model theorists, by contrast, interpret personal autonomy and agent responsibility in tenns of the looser notion of 'control'. From this perspective, conscious choosing is but one (highly responsible) instance of such control, and the presence or absence of mental states is primarily relevant to detennining degrees of responsibility. The examination of these two models occupies the bulk of this manuscript. Exploration of the capacities model and criticism of the orthodox view also generate treatment of legal issues such as the use of negligence liability, the nature of criminal omissions, the character of various legal defenses, and so on. Chapters 2 and 3 set out some of the thematic arguments outlined above and introduce tenninology and useful distinctions. Chapters 4 through 7 provide substantive analyses of agent responsibility and of standards of criminal liability. In these chapters, I argue for the comparative superiority of the capacities model of responsibility and offer recommendations for changes in current legal conceptions and standards of liability. Each chapter centers on an element of individual responsibility and related legal concerns. The final chapter, Chapter 8, comprises an overview of the integrated theory of responsibility and liability and its comparison with the traditional view.