Motor vehicle travel is the primary means of transportation in the United States, providing freedom in travel and enterprise for many people. Motor vehicle crashes are the leading cause of death for the young and contribute to a high degree of morbidity and mortality for all ages. Motor vehicle crashes produce an enormous burden for society in terms of suffering, disability, death, and costs. Motor vehicle crash injury prevention is developing as a focused discipline to implement proven interventions involving technology and behavior known to prevent or reduce the severity of motor vehicle crash injury. Emergency physicians have an important role in advocating motor vehicle safety and injury prevention, both in the emergency department and within the community.