In 2010 the total economic cost of motor vehicle crashes in the United States was $277 billion. This represents the present value of lifetime economic costs for 32,999 fatalities, 3.9 million non-fatal injuries, and 24 million damaged vehicles. These figures include both police-reported and unreported crashes. The National Highway Traffic Safety Administration (NHTSA) is charged with improving the safety of our Nation's roadways. The agency accomplishes this by regulating vehicle safety performance, enforcing existing safety requirements, and promoting programs that influence driver behaviour. This book describes the process, assumptions, and methods used by the agency to estimate the impact of its safety regulations and behavioural programs on fatality rates, and measures the impact of these programs on those rates.