Medical devices, or instruments or tools to manage disease, are increasingly used in the home, yet there have been limited evaluations of how older adults and caregivers safely use these devices. This study concerns a qualitative evaluation of (1) barriers and facilitators of appropriate use, and (2) outcomes of inappropriate use, among older adults at the transition from hospital to home with skilled home health care (SHHC). Guided by a human factors engineering work system model, the authors (1) conducted direct observations with contextual inquiry of the start-of-care or resumption-of-care SHHC provider visit, and (2) semi-structured interviews with 24 older adults and their informal caregivers, and 39 SHHC providers and administrators. Five requirements for the appropriate use of home medical devices were identified. A systems approach integrating the hospital with the SHHC agency is needed to make the use of home medical devices safer.