The health of incarcerated populations is intertwined with the health of security staff, but the social mechanisms, and especially the specific interventions, that might mitigate these health harms are underexplored. We examine one possible mechanism of interrelated health harms: whether and how jail security staff are willing and able to care for mentally ill detainees. We hypothesize that the attitudes of security staff towards care affect the well-being of everyone in a jail setting—staff, as well as detainees. Analyzing 539 anonymous respondent surveys administered to a stratified cluster sample of security staff working in a large U.S. county jail system, we (1) describe the prevalence of a perceived duty to care and availability of caring resources among security staff and (2) analyze whether variations in a duty to care and caring resources predict outcomes associated with staff and detainee well-being. Across five maximum likelihood models estimated, both perceived duty to care and availability of caring resources are significantly associated with collaborative relationships with medical staff, increased perceptions of personal safety, decreased frequency of hostile encounters, and better self-reported health outcomes. Our models explain 20 percent of the variation in self-reported health outcomes (R2 = .20), a meaningful effect of care on security personnel's well-being. Our findings suggest security staff have an often-overlooked duty to care akin to that experienced by healthcare staff. Among healthcare staff, dual loyalty trainings have successfully amplified caring duties relative to security duties; similar trainings for security staff might better leverage their caring duties to improve both staff and detainee well-being.