Are races real? Is race a biological or social category? What role, if any, does race play in scientific explanations? This Cambridge Element addresses these and other core questions in the metaphysics of race. It discusses prominent accounts of race such as biological racial realism, social constructivism about race, and racial anti-realism. If anti-realists are right, our societies find themselves in thrall to a concept that is scarcely more veridical than 'witch' or 'werewolf'. Social constructionism grounds race in factors ultimately controlled by human thought and action. Biological racial realists argue that race is too quickly dismissed as biologically meaningful, and that it has a role to play in contemporary life sciences. The Element explores these views and shows their virtues and shortcomings. In particular, it advances an argument against biological racial realism that draws on the metaphysics of naturalness and philosophy of biology and medicine.