The transitions that have occurred in medicine have given shape to the existing system of delivering healthcare in the US (Starr, 1982). However, scientific discoveries are only one factor in the design of the current US healthcare delivery system. It is the intent of this chapter to explore the historical trends and issues influencing healthcare, describe the development of the nurse practitioner as a provider of healthcare services, and provide several case studies that depict the impact of managed care on this role as it exists today. The rationale for exploring the development of this advanced practice role in detail is that without a view of the past the future cannot be understood.