DescriptionIn this dissertation, I defend the affect program hypothesis, the proposal that emotions are governed by programs that coordinate prototypical patterns of emotional response. I respond to two heterogeneity problems for affect program—the problem of heterogeneity within an emotion type and the problem of heterogeneity across emotion types—with the ultimate goal of explaining how affect program theory can accommodate complex emotions. Any theory of emotion must be able to explain (a) how to account for the apparent regularities in emotional response among a certain subset of emotion types, the basic emotions, and (b) how complex emotions are (or are not) related to the subset of basic emotions. I argue that an account of (b) is based upon a strong version of the affect program hypothesis, and that relaxing the account of (a) opens up the possibility that affect programs can account for (b), not only explaining the basic emotions happiness, sadness, anger, disgust, fear, and surprise, but also more complex emotions, like shame, guilt, awe, horror, and composite states like ‘shame-horror-joy’ and ‘resentment-shame-annoyance-guilt’.