Public-private partnerships have been common in infrastructure for many years and are increasingly being considered as a means to finance, build, and manage hospitals. However, the growth of hospital PPPs in the past two decades has led to confusion about what sorts of contractual arrangements between public and private partners consititute a PPP, and what key differences distinguish public private partnership for hospitals from PPPs for infrastructure. Based on experiences from around the world we indentify six key areas where hospital PPPs differ from infrastructure partnerships. We draw upon the hospital partnerships that have been documented in OECD countries and a growing number of middle-income countries to identify four distinct types of hospital PPPs: service focused partnerships in which private partners manage operations within publicly constructed facilities; facilities and finance PPPs, focused on mobilizing capital and creating new hospitals; combined PPPs, involving both facility and clinical operations; and co-located PPPs where privately operated services are developed within the grounds of a public hospital. These four types of hospital PPPs have differing goals, and therefore different contractual and functional aspects, as well as differing risks to both public and private partners. By clarifying these, we provide a base upon which hospital PPPs can be assessed against appropriate goals and benchmarks.