Values are a key motivational basis for decision making and for behaviour (see, e.g., Rokeach, 1973; Schwartz, 1992). This includes the sport context, where competitors often have to resolve a value-based conflict -- to do whatever it takes in order to win or to play fairly and perhaps reduce the chances of winning. An established theory of value conflicts and compatibilities can explain the basis for such conflicts in sport. In this chapter we present this theory, locate values specific to the sport context within the structure of basic values, and therefore provide a better understanding of value conflicts in sport. Theory and knowledge on value change is then used to provide a basis for value interventions in order to promote fair play values and behaviours.