Simulation is effective at improving healthcare students' knowledge and communication. Despite increasingly interprofessional approaches to medicine, most studies demonstrate these effects in isolation. We enhanced an existing internal medicine curriculum with immersive interprofessional simulations. For ten months, third-year medical students and senior nursing students were recruited for four, 1-hour simulations. Scenarios included myocardial infarction, pancreatitis/hyperkalemia, upper gastrointestinal bleed, and chronic obstructive pulmonary disease exacerbation. After each scenario, experts in medicine, nursing, simulation, and adult learning facilitated a debriefing. Study measures included pre- and post-tests assessing self-efficacy, communication skills, and understanding of each profession's role. Seventy-two medical students and 30 nursing students participated. Self-efficacy communication scores improved for both (medicine, 18.9±3.3 pretest vs 23.7±3.7 post-test; nursing, 19.6±2.7 pretest vs 24.5±2.5 post-test). Both groups showed improvement in "confidence to correct another healthcare provider in a collaborative manner" (Δ=.97 medicine, Δ=1.2 nursing). Medical students showed the most improvement in "confidence to close the loop in patient care" (Δ=.93). Nursing students showed the most improvement in "confidence to figure out roles" (Δ=1.1). This study supports the hypothesis that interdisciplinary simulation improves each discipline's self-efficacy communication skills and understanding of each profession's role. Despite many barriers to interprofessional simulation, this model is being sustained. © 2014 Society of Hospital Medicine.