Simplistic accounts of egoism have encouraged incomplete and superficial answers to the question Why should I be moral? This work defends an interpretation of the question as a genuine and fundamental question of practical importance. Detailed description of the egoist's planning, language use and reason-giving provide a strongest-case analysis of the amoral egoistic option, in the spirit of Plato's account of the perfectly unjust man. The framework for an answer is offered which draws out key theoretical assumptions and practical consequences of an egoistic system whose potential adaptability has been consistently underestimated.