The question of how white physicians in the colonial West Indies thought about race lies at the heart of Tim Lockley’s new book on the nineteenth-century West India Regiments (WIRs), and undergirds Suman Seth’s study of eighteenth-century medical debates. Seth argues that heated disagreements (one even involving a dual to the death) over colonial medicine, medical authority, and the role of geography played an important part in the development of racial categories during the eighteenth century. Picking up where Seth’s story ends, Lockley’s book argues that military officers’ reports on the WIRs demonstrated changing ideas about race in the British Atlantic from the 1790s through the 1870s. Both books demonstrate the intertwined nature of race and medicine in the colonial Caribbean.