Checklists have been shown to improve surgical safety in randomized controlled trials, but they have had varied impact when implemented in clinical practice. This interrupted time-series study examined surgical mortality before, during, and after implementation of the WHO surgical safety checklist. The rate of surgical mortality declined more during checklist introduction than it had before or after implementation, and hospital mortality did not decline among nonsurgical patients during the same time interval. The investigators, including checklist pioneer Atul Gawande, conclude that perioperative mortality has declined in association with checklist implementation. Past PSNet interviews with Lucian Leape and David Urbach discussed their perspectives on surgical safety checklists.