Among the many risk factors that contribute to young drivers' crash involvement, two are
critical: peer passenger presence, which is unique to young drivers, and the influence of
alcohol, a universal risk for drivers but one against which young drivers are most
susceptible. Clarification of how passenger presence interacts with alcohol consumption to
increase risk is needed. The impact of experimentally manipulated passenger characteristics
and alcohol quantity on risky driving is observed using driving simulation and a random
assignment experimental design with a sample of 18-21 year old male and female drivers.