The effect of differences in the legal minimum licensing age on fatal motor vehicle crashes was studied in New Jersey (age 17), Massachusetts (age 16 1/2), and Connecticut (age 16). New Jersey's 17-year-old licensing law was associated with greatly reduced fatal crash involvement. It is estimated that 65 to 85 per cent reductions in 16 year-old-driver fatal crash involvement can be expected if the licensing age is increased from 16 to 17 without increasing fatal crash rates at older ages.