This book offers a model for understanding autonomy in the context of the practical uses of this concept for applied ethics and political philosophy, and in particular for our understanding of moral responsibility. The first half of the book develops a concept of autonomy understood in terms of the Aristotelian notion of ‘helmsmanship’, and argues that autonomy must be understood in these terms if it is to serve a useful role for practical issues in applied ethics. The second half of the book delves into our understanding of autonomy and its relationship to various forms of authority, especially law. Along the way, it explores the threat which a variety of forms of obligation might and might not pose to autonomy, and offers a model for understanding the limits which must be placed on authority if it is to remain consistent with autonomy.