In this lecture delivered to the New England Surgical Society, Lucian Leape reviews the history of the movement to improve patient safety and health care quality. He discusses the role of human factors and systems thinking in analyzing and improving safety and cites the seminal Keystone ICU study as an example of the role of standardization in improving health care. Leape advocates for just culture—a balance between systems approaches and individual accountability—and urges physicians at all levels to actively participate in safety initiatives. In contrast to other observers, Leape notes that the pace of improvement in safety compares favorably with advances in clinical care. Dr. Leape discussed his remarkable career in an AHRQ WebM&M Perspective in 2006.