Medication reconciliation aims to prevent adverse events during transitions of care, but implementing effective interventions supporting medication reconciliation has proven challenging. Building upon lessons learned in the MARQUIS1 study, this pragmatic quality improvement study (MARQUIS2) implemented a refined toolkit including system-level and patient-level interventions as well as physician mentors providing remote coaching and in-person site visits. Across 17 hospital sites, the intervention was associated with a significant decrease in unintentional mediation discrepancies over time.