A graduated licensing program phases in driving experience for younger drivers, allowing beginners to gain experience under lower-risk conditions first, then gradually increasing to more complex driving situations over a period of time. In most states, the graduated period begins at age 15 or 16 and progresses to a full driver's license by the time the teens reach 17 years of age.

A graduated system provides for an initial learning period of supervised driving, followed by an intermediate period of unsupervised driving that often comes with nighttime-driving and passenger restrictions. However, even with these "bans," some states don't allow police to stop teens solely for violating nighttime and passenger restrictions.

Not all state programs are the same and according to the Institute for Highway Safety (IIHS), which grades states on their programs, no state has an optimal graduated licensing system. However, with significant state legislative advances over the last few years, no state earns the IIHS' lowest rating of "poor" for its graduated licensing program.

Graduated licensing is important for teens and those who have to share the road with them. Motor vehicle crashes are the leading cause of death among 15- to 20-year olds. In 2005, drivers age 15 to 20 made up 4.7 percent of the driving population yet they accounted for 12.6 percent of all drivers involved in fatal crashes and 16 percent of all drivers involved in police-reported crashes, according to the U.S. Department of Transportation. Twenty-three percent of teen drivers killed were intoxicated.

Among licensed drivers, teens between the age of 15 and 20 have the highest rate of fatal crashes relative to other age groups, including the elderly.

And graduated licensing programs have been shown to work. Fatal and injury crash data from California's Statewide Integrated Traffic Records System reported that in the first three years of the new graduated license program implemented in the state in 1998, the average number of teenage passengers carried by 16-year-old drivers decreased by approximately 25 percent. Even without considering the beneficial effect of a decrease in the crash rate, the decrease in the number of teenage passengers in actual crashes resulted in an estimated saving of eight lives and the prevention of 684 injuries over a three-year period, California reported.

For graduated licensing details for your state, see State-by-state provisions for teenage drivers.