This chapter explains the notion that is probably even more slippery: motivation. Yet, unlike consciousness, which some regard as helpful and others as hurtful, experts and amateurs alike agree unanimously that motivation is a very important, if not the most important, factor in language learning. It contributes to this agenda by discussing the educational psychology of intrinsic motivation. Research on intrinsic motivation and achievement suggests that there is a very delicate balance between a person's experience of competence and external feedback. Language educators agree with admirable unanimity on the supreme importance of motivation in language learning. Placing an undue emphasis on threats, monetary rewards, or grades, may suppress the energizing forces of intrinsic motivation and all the crucial stimulants for learning it carries with it: focused attention, positive affect, depth of processing, intensity of engagement, and so on. Personal achievement, in terms of knowledge, skills, and rewarding social relationships, is tied to intrinsic motivation through the person's self-determination and autonomy.