Mayo Clinic implemented an Electronic Health Record (EHR) in a complex, geographically diverse healthcare system, with more than 60,000 end users and 4700 physicians using five geographical go-lives. While typical EHR readiness activities focus on training individuals to perform their roles, Mayo Clinic focused on helping its users learn and practice multidisciplinary workflows. Over 300 simulation scripts and accompanying content were used over the course of the final four go-lives, and end users were surveyed via a RedCAP (TM) Survey. Respondents at the four sites that used simulations identified the simulations as the most helpful readiness activity. End users highly valued simulations across geographies whether in a community-based or a tertiary/quaternary care system. This is the first description of the large-scale use of simulations during an EHR implementation to ready physicians and staff to perform multidisciplinary workflows.