Faculty modeling of desired behaviors has historically been a part of the apprenticeship model of clinical teaching, yet little is known about best practices for modeling. This study compared the educational impact of implicitly versus explicitly modeled communication skills among U.S. medical students. Fourth-year medical students from six U.S. academic medical centers were randomly assigned one simulated clinical encounter in which faculty provided either implicit or explicit modeling of important communication skills. Outcomes were assessed by electronic surveys immediately before and after the simulations. Students were blinded to the purpose of the study. Students in the explicit arm were more likely to correctly cite two of the three key specific communication elements modeled by faculty: deliberate body position (53.3% vs. 18.6%, p < 0.001) and summarizing patient understanding (62.2% vs. 11.6%, p < 0.001). More students in the explicit study arm reported faculty ‘demonstrated a key behavior that they wanted me to be able to perform in the future’ (93.2% versus 62.8%, p = 0.002). Participating faculty stated they would modify their teaching approach in response to their experiences in the study. In a multi-center randomized trial, explicit faculty role-modeling led to greater uptake of communication knowledge, greater recognition of skills, and a greater sense that faculty expected these skills to be adopted by students. These results must be considered in the context, however, of a simulated environment and a short timeframe for assessing learning with students who volunteered for a simulated experience.