iO automobile drivers whose driving involved them in accidents serious enough to require hospitahzation were paired with SO drivers without accident histories but matched according to sex, approximate age, race, and educational level. The Ss were compared on the basis of their driving experiences and performance on written tests. The accident victims differed from the comparison Ss in a higher incidence of previous traffic violations but were not distinguishable from the comparison Ss on any written tests. The accident Ss were similar to the "safe" drivers in describing themselves as much closer to "expert" than "very poor" on a driving performance continuum. In fixing the responsibility for the accidents and in estimating their driving competence at the time of the accidents, the accident Ss' reports are at considerable variance with police reports.Traflk accidents, have been described as relatively infrequent phenomena, determined by multiple, not single, factors and, in the main, determined by more than one personall this in a constantly shifting environment. Traffic accidents for the entire country in 1960 resulted in 38,200 persons killed, 1,400,000 disabling injuries, and an estimated total cost of $6,500,000,000 (National Safety Council. 1960). Accidents rank first in the cause of death in ages 1 to 24 and are second in ages 25 to 64 with traffic accidents being far more common than any other type of accident. Traffic accident research has focused on traffic engineering, vehicle design, and physical and psychological driver characteristics (Mc-Farland, Moore, & Warren, 1955). Yet there is no consistent understanding of or agreement about the basic causes of traffic accidents. Attitudes, judgments, and other psychological characteristics of drivers are conceded to be ultimately important in the epidemiology of traffic accidents (Brody, 1959; Conger, Gaskill, Glad, Hassel, Rainey, & Sawrey, 1959;Forbes. 1953). Many investigators concerned with traffic research and driver education have long searched for a single, objective, easily administered instrument to differentiate the competent from the incompetent driver.