I argue that emotion is an ontologically emergent and sui generis. I argue that emotion meets both of two individually necessary and jointly sufficient conditions for ontological emergence. These are, (i) that emotion necessarily has constituent parts to which it cannot be reduced, and (ii) that emotion has a causal effect on its constituent parts (i.e. emotion demonstrates downward causation). I argue that emotion is partly cognitive, partly constituted by feelings and partly perceptual. 1) I argue that both the type and the intensity of an emotion supervene on cognitive factors. But emotion cannot be reduced to cognition because emotions are paradigmatically valenced and cognitions are not. 2) I argue that the phenomenal properties of emotion are determined by bodily feelings, thus emotion necessarily requires feelings. But emotion cannot be reduced to feelings because emotion has rational properties not held by bodily feelings. 3) I argue that the intentional objects of emotion are perceptual objects, and hence emotion necessarily requires perception. But emotion cannot be reduced to perception because emotion has second orders (as evidenced by metaemotion) and perception does not. Thus emotion meets the first necessary condition for ontological emergence; emotion has constituent parts to which it cannot be reduced. I go on to argue that emotion has a causal effect on its 4) cognitive, 5) feeling, and 6) perceptual parts, both as a faculty and at the level of the individual emotion. Emotion meets the two individually necessary and jointly sufficient conditions for ontological emergence: (i) emotion has composite parts to which it cannot be reduced, and (ii) emotion has a causal effect on its composite parts. Thus emotion is ontologically emergent. Being ontologically emergent, emotion is sui generis.