Throughout the history of medicine, patients who had a disease that was poorly understood were advised to rest. As scientists and doctors learned more, early mobilization and active therapies (e.g., exercise) gradually replaced rest as the conventional treatment for a variety of medical conditions, such as chronic fatigue, whiplash, stroke, low back pain, and cardiac arrest. We have now reached this same juncture for concussion care. The proposed project aims to figure out how to support doctors in implementing new science-informed return to activity guidelines for concussion.