In this chapter, a theory is developed which posits that the intensity of the response to humorous presentations critically depends upon the respondent’s affective disposition toward the protagonists involved. Specifically, it is proposed that humour appreciation is facilitated when the respondent feels antipathy or resentment toward disparaged protagonists and impaired when he feels sympathy or liking for these protagonists. The generality of the theory is established by demonstrating that alternative notions, such as the reference - group theory of humour, are specific cases of disposition theory. The disposition theory is also shown to cope effectively with a variety of conditions which alternative notions cannot account for. The explanatory power of the various models is discussed in the light of available research evidence. Finally, the disposition theory of humour is expanded into a disposition theory of mirth, in order to explain appreciation deriving from non-humorous entertaining presentations.