In this study, the authors designed checklists to guide care during operating-room crises and evaluated them in a simulated operating room. The availability of checklists improved adherence to best practices by operating-room teams during simulations of surgical crises. Operating-room crises (e.g., massive hemorrhage and cardiac arrest) are high-risk, stressful events that require rapid and coordinated care in a time-critical setting. The reported incidence may be rare for an individual practitioner, 1 but the aggregate incidence for a hospital with 10,000 operations a year is estimated to be approximately 145 such events annually. 2 These are situations in which the way the team cares for a patient will make the difference between life and death. Failure to effectively manage life-threatening complications in surgical patients has been recognized as the largest source of variation in surgical mortality among hospitals. 3 – 7 Small-scale studies . . .