One aim of this chapter is to fill out the account of the fair-play theory of obligation sketched in previous chapters. In particular, I show how respect for the rule of law is an integral feature of fair-play theory. In most of the chapter, however, the elaboration proceeds by defending the theory against six important objections critics have lodged against it. One objection, raised memorably by Robert Nozick, would have us reject the principle of fair play altogether. The others allow that the principle is valuable and unobjectionable when confined to its proper sphere, but they insist that political obligation exceeds the boundaries of that sphere. In addition to defending the fair-play account against these objections, I also argue against those who believe that fair play is a necessary but insufficient element in a theory of political obligation that must be pluralistic if it is to be successful.