<p>The effect of the number of passengers on risky driving behaviors seems to be age-dependent, possibly because the injunctive norms of passengers vary with age. Therefore, the present study examined how passengers’ injunctive norms (risk-averse vs. risk-accepting) moderated the effect of the number of passengers (0, 1, or 2) on risky driving behaviors of young adult Chinese drivers during virtual driving. The passengers were female virtual young adults, and the risky driving behaviors were indexed by failure to stop immediately at the red light, overtaking slow cars, and left-turn latency. It was found that injunctive norms moderated the effect of the number of passengers on overtaking slow cars and left-turn latency. Drivers overtook more slow cars and gave way to fewer straight-ahead cars when carrying risk-accepting passengers compared to risk-averse ones, and this effect strengthened as the number of passengers increased. Furthermore, drivers overtook fewer slow cars and gave way to more straight-ahead cars as the number of risk-averse passengers increased. These findings might not only help bridge theoretical gaps in understanding how the number of passengers and their injunctive norms influence risky driving, but also provide practical insights for developing legislation and interventions to reduce risky driving behaviors and traffic accident rates in China.</p>