To assess the effect of California’s graduated driver’s license (GDL) law in San Diego County, we compared motor vehicle crash and passenger injury rates involving 16-year-old drivers for 1999 and 2000, the first two years of the law, against 1997, using data from a statewide database of all injury crashes. While the crash rate per 1,000 drivers did not change following GDL, a significant decline in the percentage of 16-year-olds with a driver’s license corresponded with large decreases in population-based crash and injury rates.