Despite the extensive publicity that checklists have received as a result of their central role in seminal patient safety programs, hospitals are increasingly recognizing that checklists are not a panacea. A qualitative analysis of the Keystone ICU project found that many factors beyond the checklist itself were central to the project’s success, including development of a culture of safety. This Dutch study sought to evaluate both the uptake and the impact of the World Health Organization’s surgical safety checklist at a tertiary care hospital. The investigators found that full use of the checklist was strongly associated with decreased postoperative mortality, but patients for whom the checklist was only partially completed, or not completed at all, did not derive any benefits. Cultural and implementation factors likely influence checklist usage, and organizations must consider these factors carefully when attempting to encourage use of even proven checklists.