Labor played a central role in nineteenth-century penitentiaries. It was intended to provide guidance and discipline to prisoners whose behavior was outside of social, moral, and economic norms. This article examines the relationship between medicine and labor in Canadian federal penitentiaries between 1867 and 1900. As penitentiaries grew and expanded throughout the century, increasing numbers of prisoners were unable to participate in penitentiary labor due to illness or disability. In these cases, penitentiary medicine helped form part of an “enlightened” response to nonworking prisoners. It suggests that medical records from this period demonstrate how penitentiaries reconciled nonworking prisoners with the prevailing model of reform constructed around labor. The article looks at two such groups. The first is sick prisoners, including physical and mental ailments. Mental illness was an increasingly vexing problem for penitentiaries in this era as they struggled to form appropriate responses to mentally ill prisoners within the prevailing penitentiary model. The second group is prisoners with disability, including physical and intellectual disability. Although both groups were understood through medical categories, their status as “unproductive” prisoners sometimes played a larger role in determining their experience of confinement. The article looks at the influence of ideas about labor on the delivery of medical services in penitentiaries and the resulting experience of illness. Although prison medicine in Canada expanded and improved throughout this period, the sick and disabled often experienced marginalization and moral condemnation on the basis of their uncertain relationship to penitentiary labor.