Fatal crash-involved drivers of passenger vehicles were identified in the Fatality Analysis Reporting System for the period 1990 through 1995. Each driver was categorized as being alone in the vehicle at the time of the crash or with one or more passengers. Drivers at fault or responsible for crash occurrence were defined as all drivers involved in a single-vehicle crash, or drivers in multiple-vehicle crashes who were coded in the Fatality Analysis Reporting System as committing one or more driver errors. The results indicated that passenger presence was associated with proportionately more at-fault fatal crashes for drivers aged 24 and younger, were a neutral factor for drivers aged 25-29, and were associated with fewer at-fault involvements for drivers aged 30 and older. Relative risk of fatal crash involvement was particularly high for teenage drivers traveling, day or night, with two or more teenage passengers. Additional research is needed to determine how the added risk associated with teenage passengers riding with teenage drivers can be reduced or eliminated.