Emotion Review, Ahead of Print. To make progress related to long-standing questions related to the nature of emotion, we offer the Interactive Activation and Competition framework for Emotion. The IAC-E is not another conventional theory of emotion. Rather, it offers a neural-network-based, algorithmic account of how emotion instances and categories arise. Our approach suggests that there need not be a contradiction between instances of the same emotion being sometimes consistent and sometimes variable. Similarly, there need not be a contradiction between observations of homogeneity and heterogeneity within emotion categories.