Emergency departments (EDs) are at high risk for medical errors. Checklist implementation programs have been associated with improved patient outcomes in other high-risk clinical settings and when used to address specific aspects of ED care. The aim of this study was to develop an ED Safety Checklist with broad applicability across different international ED settings. Athree-round modified Delphi consensus processwasconductedwith a multidisciplinary and multinational panel of experts in emergency medicine and patient safety. Initial checklist items were identified through a systematic review of the literature. Each item was evaluated for inclusion in the final checklist during two rounds of web-based surveys and an online consensus meeting. Agreement for inclusion was defined a priori with a threshold of 80% combined agreement. Eighty panel members from 34 countries across all seven world regions participated in the study, with comparable representation from low- and middle-income and high-income countries. The final checklist contains 86 items divided into: (1) a general ED Safety Checklist focused on diagnostic evaluation, patient reassessment, and disposition and (2) five domain-specific ED Safety Checklists focused on handoff, invasive procedures, triage, treatment prescription, and treatment administration. The checklist includes key clinical tasks to prevent medical errors, as well as items to improve communication among ED team members and with patients and their families. This novel ED Safety Checklist defines the essential elements of high-quality ED care and has the potential to ensure their consistent implementation worldwide.