Beginning with an overview of the overdetermination debate and the issue of the motivational sufficiency of duty for moral conduct, this dissertation evaluates the role of feelings and sensibility in Immanuel Kant's moral philosophy. Adhering to the position that Kant's conception of agency is closely linked to the non-empirical or pure character of duty, I argue that nonetheless Kant bestows considerable leeway to the presence and exercise of various feelings, inclinations and feelings in his mature moral philosophy. This dissertation groups Kant's treatments of these empirical elements under a set of roles: motivational, aesthetic, supporting and surrogate. Barring the feeling of respect, these roles do not directly contribute to the motivation of the moral agent but rather underscore the various ways that certain feelings, desires, and inclinations function in shaping and refining the individual's receptivity to morality and duty as well as facilitate the accomplishment of discrete and determinate moral obligations. Moreover these roles address what I call affective deficits, that is, potential obstacles to the promotion of a life of virtue, such as the inextirpable character of intrinsic evil, unrefined receptivity to moral interest such as excessive reliance upon physical gratification, and a whole host of sensuous feelings and inclinations that divert one to the promptings of self-interest over the call of duty. These roles do not supplant motivation by duty but rather entail the manner in which practical reason invests certain sets of feelings, inclinations and affects with a part in sustaining and aiding in moral conduct.