This chapter describes the structure and trends of postacute care (PAC) in the United States and includes an overview of each of the types of providers, including the provider definition and characteristics, the provider payment system, and, where available, patient characteristics and quality data. It also describes the clinical and nonclinical factors associated with PAC utilization. The chapter discusses the current issues facing PAC providers and efforts to reform the delivery of health care services in the United States. Skilled nursing facilities (SNFs), the most numerous of the PAC providers, are certified by the Centers for Medicare and Medicaid Services to provide skilled nursing and therapy services. Utilization of PAC services increased when acute care lengths of stays (LOS) decreased. As further changes in health care delivery systems take place, undoubtedly more changes in PAC utilization will also occur.