Despite serious and widespread efforts to improve the quality of health care, many patients still suffer preventable harm every day. health care workers strive to do no harm, yet every year millions of patients in the U.S. are harmed during- the course of their care, and many die from preventable adverse events. Hospitals find improvement difficult to sustain, and they suffer “project fatigue” because so many problems need attention. High-reliability science is the study of organizations in industries like commercial aviation and nuclear power that operate under hazardous conditions while maintaining safety levels that are far better than those of health care. Adapting and applying the lessons of this science to health care offer the promise of enabling hospitals to reach levels of quality and safety that are comparable to those of the best high-reliability organizations. As an industry, health care should formally adopt the goal of zero patients harmed. Joint Commission President and CEO Dr. Mark Chassin delves into the promising steps healthcare organizations can take to achieve this goal.