Although improving diagnosis is a critical patient safety priority, few interventions have been tested, especially in outpatient settings. This pre–post study examined whether a "diagnostic pause," a type of checklist, could improve outpatient diagnostic safety. The team used an electronic health record–based automated trigger to identify patients at risk for missed diagnosis—patients presenting for an urgent care visit who had a previous urgent care visit within 2 weeks. At the second visit, the clinician received a prompt to reflect on the diagnosis and a short survey about how the prompt affected their actions. Participating clinicians responded to about 60% of the prompts they received and reported changing their actions 13% of the time. The authors conclude that identifying challenging diagnoses and supplementing clinicians' current diagnostic pathways requires further research.