Cerebral concussion is an entity common primarily to collision and contact sports, but which can occur in any environment. The mechanisms of injury can include direct trauma, rotational, acceleration/deceleration forces, forces transmitted to the head as a result of force to another part of the body or through a series of blows. Subsequent classifications include Grade I (mild). Grade II (moderate) and Grade III (severe). Although the primary designating factors include the effect on consciousness and memory, the evaluator must be aware of additional signs and the potential for a deteriorating condition due to hemorrhage. A review of common injury mechanisms, signs, symptoms, evaluation process, grading, emergency care, and guidelines for return to participation and injury prevention are presented.