This course will explore how natural philosophers and scientists have defined, used, and sometimes challenged ideas about race from the eighteenth century to today. Using a range of primary and secondary sources, we will examine how scientific ideas about race developed in concert with European imperial expansion and slavery; how these ideas were employed in legal cases, medical practice, and eugenics policies; and how activists and scholars have challenged racist practices and ideas. Finally, we will turn to the recent resurgence of racial thinking in biology and medicine in the light of the history of race and science.