This article is a review and analysis of the Mann Gulch fire disaster, an event made famous in Norman Maclean's award–winning book, Young Men and Fire (1992). Using the story of a firefighter who improvised a response to a fire by setting a back-fire while the rest of his crew panicked and ultimately perished, Weick examines the disintegration of role structure and sensemaking within an organization. He discusses sources of resilience that make groups less vulnerable, including improvisation, virtual role systems, the attitude of wisdom, and norms of respectful interaction. The purpose is to understand why organizations unravel and how they become more resilient. The organizational literature is reviewed to demonstrate a need for reexamination of successful group structures. Weick's work influenced many others who have written about improving safety, particularly in teams that work in fast-moving and ambiguous clinical settings.