Checklists of evidence-based interventions have resulted in notable successes in patient safety, particularly in preventing central line–associated bloodstream infections. This randomized controlled trial attempted to extend the checklist approach to prevention of surgical site infection. However, despite implementing five evidence-based practices in a bundled approach, the incidence of postoperative infections was actually higher in the intervention group compared with patients receiving standard infection prophylaxis. A commentary by the developers of the Keystone ICU checklist discusses the utility and limitations of checklists in improving safety.