This chapter focuses on urgent care centers as a unique innovation that has been in the making for the last 30 years. Urgent care centers provide unscheduled or walk-in care, are open for extended hours on weeknights and weekends, and provide services that go beyond what primary care physicians provide, such as occupational medicine, laboratory tests, and fracture care such as splinting and casting, with some providing intravenous fluids, routine immunizations, and primary care services. This chapter describes in-depth the history and growth, operations, and stakeholders of urgent care centers, and overviews the research that relates to quality of care, costs, and patient satisfaction in these centers. Given the expanding industry, strong growth in company numbers, greater employment opportunities, and rising per-capita usage of urgent care centers, the author argues that the urgent care industry is in the growth phase of its life cycle.