BACKGROUND: Multi-institutional, international practice variation of pediatric anaphylaxis management by health care providers has not been reported. OBJECTIVE: To characterize variability in epinephrine administration for pediatric anaphylaxis across institutions, including frequency and types of medication errors. METHODS: A prospective, observational, study using a standardized in situ simulated anaphylaxis scenario was performed across 28 health care institutions in 6 countries. The on-duty health care team was called for a child (patient simulator) in anaphylaxis. Real medications and supplies were obtained from their actual locations. Demographic data about team members, institutional protocols for anaphylaxis, timing of epinephrine delivery, medication errors, and systems safety issues discovered during the simulation were collected. RESULTS: Thirty-seven in situ simulations were performed. Anaphylaxis guidelines existed in 41% (15 of 37) of institutions. Teams used a cognitive aid for medication dosing 41% (15 of 37) of the time and 32% (12 of 37) for preparation. Epinephrine autoinjectors were not available in 54% (20 of 37) of institutions and were used in only 14% (5 of 37) of simulations. Median time to epinephrine administration was 95 seconds (interquartile range, 77-252) for epinephrine autoinjector and 263 seconds (interquartile range, 146-407.5) for manually prepared epinephrine (P = .12). At least 1 medication error occurred in 68% (25 of 37) of simulations. Nursing experience with epinephrine administration for anaphylaxis was associated with fewer preparation (P = .04) and administration (P = .01) errors. Latent safety threats were reported by 30% (11 of 37) of institutions, and more than half of these (6 of 11) involved a cognitive aid. CONCLUSIONS: A multicenter, international study of simulated pediatric anaphylaxis reveals (1) variation in management between institutions in the use of protocols, cognitive aids, and medication formularies, (2) frequent errors involving epinephrine, and (3) latent safety threats related to cognitive aids among multiple sites.