Bridging psychological research exploring emotional complexity and research in the natural sciences on the measurement of biodiversity, we introduce-and demonstrate the benefits of-emodiversity: the variety and relative abundance of the emotions that humans experience. Two cross-sectional studies across more than 37,000 respondents demonstrate that emodiversity is an independent predictor of mental and physical health-such as decreased depression and doctor's visits-over and above mean levels of positive and negative emotion. These results remained robust after controlling for gender, age, and the 5 main dimensions of personality. Emodiversity is a practically important and previously unidentified metric for assessing the health of the human emotional ecosystem.