Competitive sport, both at high and lower performance levels, represents an ethically contested field. One the one hand, sport represents ideal values; fairness and equality of opportunity, mutual respect between participants, winning and losing with dignity, and human excellence. On the other hand, sport can be a cynical sphere and a struggle for prestige and profit by all available means; performance-enhancing drugs, corruption, and violence. How can the moral potential of sport be realized? What are sport’s normative ideals? One classic response to these questions is a reference to the ideal of fair play. Here, I present a brief sketch of the historical background of the ideal and how the concept of fair play has been treated in the sport philosophical literature. In the main parts of the chapter, I discuss an updated interpretation of fair play of relevance in modern, competitive sport.