We were in a large trauma hospital, and like many hospitals, it was becoming aware of the problem of patient safety. How was it going to protect patients from preventable adverse events? The nurse manager had a clear idea about the source of risks for patients: It lay with her unreliable, unsafe nurses who made mistakes. They made mistakes with patient identi‹cation and mistakes with dosage and drug administration. They violated rules and routines related to infusion devices. They made mistakes in drug selection and labeling. They made mistakes when informing doctors or family or mistakes in doing whatever else they were asked.