PHYSICIANS TRADITIONALLY HAVE BEEN relatively independent of hospitals and have used them as “workshops” in which to carry out their professional services.1 In the prevailing medical staff model, physicians and hospitals did not have a typical market relationship: They neither bought services from nor competed with each other. Rather, physicians and hospitals informally exchanged physicians’ use of the hospital’s facilities for carrying out responsibilities, such as serving on quality and utilization review committees and taking emergency department (ED) call, as obligations for having medical staff privileges.2 As a response to managed care in the 1990s, new organizational arrangements between physicians and hospitals were initiated but then largely abandoned as the use of capitation to pay providers began a rapid decline by the late 1990s that continued into the new century. Hospitals began to shift their focus from building physician-hospital organizations (PHOs) and related organizations to building stronger relationships with specialist physicians, to benefit from high-margin, specialized services and to try to avert potential competition with physicians in delivering outpatient services.3 This has taken the form of new approaches by hospitals to branding, marketing, and providing services—called a “service-line strategy.”4 Although closely affiliated specialist physicians are central to hospital-based service-line products, other less closely affiliated specialists are competing directly with hospitals by developing or expanding physician-owned specialty facilities of various kinds.