This book aims to develop a unified theory of political obligation and the justification of punishment that takes its bearings from the principle of fair play. Much has been written on each of these subjects, of course, including numerous essays in recent years that approach one or the other topic in fair-play terms. However, there has been no sustained effort to link the two in a fair-play theory of political obligation and punishment. This book undertakes such an effort. This introduction explains why such a theory is an attractive possibility and how the argument for it unfolds in the succeeding chapters.