On any given day, about one in 25 hospital patients in the U.S. has a healthcare-associated infection (HAI) that the patient contracts as a direct result of his or her treatment. Fortunately, the spread of most HAIs can be halted through proper disinfection of surfaces and equipment. Consequently, cleaners — “environmental services” (EVS) in hospital parlance — must take on the important task of defending hospital patients (as well as employees and the broader community) from the spread of HAIs. Nevertheless, despite the importance of this task, hospitals frequently outsource this function, increasing the likelihood that these workers are under-rewarded, undertrained, and detached from the organization and the rest of the care team. As a result, the outsourcing of EVS workers could have the unintended consequence of increasing the incidence of HAIs. We demonstrate this relationship empirically, finding support for our theory by using a self-constructed dataset that marries infection data to structural, organizational, and workforce features of California’s general acute care hospitals. The study thus advances the literature on nonstandard work arrangements — outsourcing, in particular — while sounding a cautionary note to hospital administrators and healthcare policymakers.