Few large institutions have changed as fully and dramatically as the US healthcare system since World War II. Compared to the 1930s, healthcare now incorporates a variety of new technologies, service-delivery arrangements, financing mechanisms and underlying sets of organizing principles. This book examines the transformations that have occurred in medical care systems in the San Francisco Bay area since 1945. The authors describe these changes in detail and relate them to both the sociodemographic trends in the Bay Area and to shifts in regulatory systems and policy environments at local, state and national levels. But this is more than a social history; the authors employ a variety of theoretical perspectives - including strategic management, population ecology and institutional theory - to examine five types of healthcare organizations through quantitative data analysis and illustrative case studies. Providing a thorough account of changes for one of the nation's leading metropolitan areas in health service innovation, this book is a landmark in the theory of organizations and in the history of healthcare systems.