The principle of fair play is widely thought to require simply that costs and benefits be distributed fairly. This gloss on the principle, while not entirely inaccurate, has invited a host of popular objections based on misunderstandings about fair play. Central to many of these objections is a failure to treat the principle of fair play as a transactional principle – one that allocates special obligations and rights among persons as a result of their interactions. I offer an interpretation of the principle of fair play that emphasizes its similarities to another transactional principle: consent. This interpretation reveals that playing fair requires one to reciprocate specifically by following the rules of the cooperative scheme from which one benefits, just as consent requires one to act according to the terms of an agreement. I then draw on the comparison with consent to reply to some popular and persistent objections to the principle.