Providing Sustainable Healthcare In and Out of the Hospital: Boundaries of Responsibility and their Spatiotemporal Effects This paper explores how the times and places of healthcare provision are constituted by boundaries of responsibility. It takes as an example case the role that ambulance services and patient transport play in both delivering patients and delivering care between the hospital, the home and other spaces. We argue that managing demand for healthcare services, including patient transport, depends on shifting the timespace/s of working practices in hospitals in various ways and that one way of doing this is to affect different boundaries of responsibility. We draw on examples of initiatives within the NHS that are shifting and transgressing the boundaries between hospital and home, between hospital and ambulance, and between clinical staff and ambulance staff to show where and when such changes reconfigure spatiotemporal arrangements of working practices that can improve the flow of patients into and out of hospital and support the management of demand for services and resources required. We conclude by developing the implications of such a strategy for maintaining the financial and environmental sustainability of the NHS and pointing towards other opportunities for shaping the timespace/s of working practices beyond transgressing boundaries of responsibility.