In Sex Isn’t Real, Beans Velocci traces the history of current high stakes attempts to define sex and to create a world devoid of trans life. Drawing on lab notes, family genealogies, medical case studies, and more, Velocci follows scientists and clinicians from the mid-nineteenth through the mid-twentieth century and across five disciplines—zoology, eugenics, gynecology, statistical sexology, and transsexual medicine—as their ideas and practices created a definitional tangle. They demonstrate how the sorting of bodies into male and female persists not despite but because of sex’s incoherence: the defining features of these categories shift to contain various understandings of anatomy and physiology, theories of race, developments in research and medical methodologies, and bodies that cannot be accounted for in a binary framework. Exposing the endless work required to produce a world in which most people have a binary gender identity that neatly fits their binarily sexed body, Velocci demonstrates that it is not cis people who fit the categories; it’s the categories that flex to make them fit.