A concussion is a serious injury--a mild traumatic brain injury (TBI)--that induces physiological disruption of brain function. A concussion is caused by a bump, blow, or jolt to the head or body. The sudden movement causes stretching and tearing of brain cells; cells become damaged and chemical changes occur within the brain. Concussions can lead to cognitive, academic, behavioral, and emotional problems that last beyond that initial period of seeming "dazed." Concussions have been called a "silent epidemic" because symptoms can be subtle and covert. However, several high-profile concussion cases involving professional athletes have turned media attention to concussions. Those stories, coupled with stories on the more than 300,000 troops who have sustained concussions during recent combat, have helped to increase awareness of the potential impact of concussions. Many people who sustain concussions appear to recover fully in 1 or 2 weeks. However, adolescents' brains can take several weeks longer than adults' brains to heal following a concussion. Those at risk for slower recovery include individuals with prior brain illness or injury, learning disabilities, or psychiatric disorders. Thus, school psychologists must be aware of concussion signs and symptoms, educational implications, and assessment strategies. They are also in an excellent position to initiate and sustain systems-level change by promoting prevention and intervention efforts.