Most studies of the categorization of emotions tests the prototype model against the classical model, concluding that the prototype model offers the better explanation. Prototype models, as with all similarity-based models, posit that categorization depends on the similarity between the instance to be categorized and the category representation. However, we find that emotion similarity judgments and categorization judgments sometimes diverge. Specifically, information about changes in a person`s status and/or potency is weighted more heavily in categorization decisions than it is in similarity decisions. We argue that a knowledge-based model, rather than a similarity-based model, offers the best account of emotion categorization when information about status and potency changes is available.