Health Systems Science is the first text that focuses on providing a fundamental understanding of how health care is delivered, how health care professionals work together to deliver that care, and how the health system can improve patient care and health care delivery. Along with basic and clinical science, Health Systems Science (HSS) is rapidly becoming a crucial "third pillar" of medical science, requiring a practical, standardized curriculum with an emphasis on understanding the role of human factors, systems engineering, leadership, and patient improvement strategies that will help transform the future of health care and ensure greater patient safety.