What is the structure of emotion? Emotion is too broad a class of events to be a single scientific category, and no one structure suffices. As an illustration, core affect is distinguished from prototypical emotional episode. Core affect refers to consciously accessible elemental processes of pleasure and activation, has many causes, and is always present. Its structure involves two bipolar dimensions. Prototypical emotional episode refers to a complex process that unfolds over time, involves causally connected subevents (antecedent; appraisal; physiological, affective, and cognitive changes; behavioral response; self-categorization), has one perceived cause, and is rare. Its structure involves categories (anger, fear, shame, jealousy, etc.) vertically organized as a fuzzy hierarchy and horizontally organized as part of a circumplex.