This paper defines a new pre-crash scenario typology for vehicle safety research based on the 2004 General Estimates System (GES) crash database. The purpose of this typology is to establish a common foundation for public and private organizations to develop and estimate potential safety benefits of effective crash countermeasure systems. Pre-crash scenarios portray vehicle movements and critical events immediately prior to the crash. This new typology consists of a set of 36 pre-crash scenarios representing 99.4% of all police-reported crashes that involve at least one light vehicle (i.e., passenger car, sports utility vehicle, van, mini-van, and light pickup truck). Lightvehicle crashes accounted for about 5,942,000 policereported crashes in the United States based on 2004 GES statistics. This typology is nationally representative and can be annually updated using national crash databases. This paper quantifies the severity of the scenarios in terms of annual crash frequency, economic costs, and functional years lost. Characteristics of the driving environment, driver, and vehicle are also described.