Pacific Colony, a Southern California institution established to care for the "feebleminded," justified the incarceration, sterilization, and forced mutilation of some of the most vulnerable members of society from the 1920s through the 1950s. Institutional records document the convergence of ableism and racism in Pacific Colony. Analyzing a vast archive, Natalie Lira reveals how political concerns over Mexican immigration—particularly ideas about the low intelligence, deviant sexuality, and inherent criminality of the "Mexican race"—shaped decisions regarding the treatment and reproductive future of Mexican-origin patients. Laboratory of Deficiency documents the ways Mexican-origin people sought out creative resistance to institutional control and offers insight into how race, disability, and social deviance have been called upon to justify the confinement and reproductive constraint of certain individuals in the name of public health and progress.