PURPOSE: Simulation-based training has the potential to improve team-based care. We hypothesized that implementation of an in situ multidisciplinary simulation-based training program would improve provider confidence in team-based management of severely injured pediatric trauma patients. METHODS: An in situ multidisciplinary pediatric trauma simulation-based training program with structured debriefing was implemented at a free-standing childrens hospital. Trauma providers were anonymously surveyed 1 month before (pre-), 1 month after (post-), and 2 years after implementation. RESULTS: Survey response rate was 49% (n = 93/190) pre-simulation, 22% (n = 42/190) post-simulation, and 79% (n = 150/190) at 2-year follow-up. These providers reported more anxiety (p = 0.01) and less confidence (p = 0.02) 1-month post-simulation. At 2-year follow-up, trained providers reported less anxiety (p = 0.02) and greater confidence (p = 0.01), compared to untrained providers. CONCLUSIONS: Implementation of an in situ multidisciplinary pediatric trauma simulation-based training program may initially lead to increased anxiety, but long-term exposure may lead to greater confidence. LEVEL OF EVIDENCE: II, Prospective cohort.