Four case studies--of the Department of Veterans Affairs, Sentara Healthcare, OSF HealthCare, and Johns Hopkins Medicine--document the progress achieved in the past five years by health care organizations that were early leaders in patient safety improvement. Their experience reflects an expansion of interventions from individual hospital units to whole facilities and delivery systems, including new settings such as home health care. Approaches include developing practical methods for training, coaching, and motivating staff to engage in patient safety work; designing effective tools and systems to minimize error and maximize learning; and leading change by setting ambitious goals, measuring and holding units accountable for performance, and sharing stories to convey values. Results include advancements in safety practices, reductions in serious events of patient harm, improved organizational safety climate and morale, and declines in malpractice claims. Keeping the commitment to patient safety has required sustained focus on making safety a core organizational value, a willingness to innovate and adapt, and perseverance in pursuing goals.