This consensus group from the 2008 Academic Emergency Medicine Consensus Conference, ‘‘The Science of Simulation in Healthcare: Defining and Developing Clinical Expertise,’’ held in Washington, DC, May 28, 2008, focused on the use of simulation for the development of individual expertise in emergency medicine (EM). Methodologically sound qualitative and quantitative research will be needed to illuminate,refine, and test hypotheses in this area. The discussion focused around six primary topics: the use of simulation to study the behavior of experts, improving the overall competence of clinicians in the shortest time possible, optimizing teaching strategies within the simulation environment, using simulation to diagnose and remediate performance problems, and transferring learning to the real-world environment. Continued collaboration between academic communities that include medicine, cognitive psychology, and education will be required to answer these questions.