Traffic accidents are the leading cause of death among teens in the United States. To change this statistic, many states have adopted laws that put restrictions on young drivers. But experts say parents can play an even greater role in steering their teens to safety behind the wheel.

Every year millions of American teens get behind the wheel of a car for the first time.

Sarah, 20, was just one of those new drivers a few years ago. "I started practicing driving a little bit after I turned 15. I had my full license when I was 16," she says. Her learner's permit allowed her to practice driving with an adult driver in the front seat with her.

"I practiced with my father most of the time," she says. "First, we started in parking lots. Then, we started practicing on local roads and gradually we built up to highways."

To Sarah, like most teenagers, driving a car meant freedom. However, she says, she was very careful not to repeat her older sister's mistakes.

"She had a rather unfortunate incident a few weeks after she got her license," she says. "She briefly fell asleep at the wheel and crashed into a neighbor's car. So, I learned from her you shouldn't drive when you're too tired and stay within 10 miles of the speed limit."

But a lot of teens never learn that lesson, according to Timothy Smith. As a certified driving instructor, he has always been concerned about teen safety behind the wheel. He interviewed dozens of parents, teens, driving instructors and police officers to find out why the teen accident rate is so high.

"The primary cause, in my opinion, is simply because we do not train our teen drivers adequately enough in this country," he says. "Eighty percent of all teen driver crashes are caused by driver error. That's a stunning statistic.

In his book, Crashproof Your Kids: Make Your Teen a Safer, Smarter Driver, Smith presents a series of behind the wheel exercises designed to improve a teen's driving skills. He says today, driving has become more complicated and risky than ever.

"When parents learned to drive, we had far less traffic, less road rage and far less distractions," he says. "Think about all the electronic devices we've invited to our automobiles: televisions, VCRs, DVD recorders, iPods, laptops. It's astonishing. I've seen teenagers text-message on their cell phones to other teens while driving. To help reduce those distractions, eliminate them in the beginning stages of your teen learning to drive, at least the first three to six months."

Smith says he believes that laws to regulate young drivers' activities in a car can have a major impact on teen crash rates. "The vast majority of states, over 40 states, now have some kind of graduated licensing laws," he says. "Some of the laws that are now being passed by states increase the driving age, increase the amount of hours of the parental supervision and ban the use of the cell phones. These are all really positive developments."

Maryland is considered a model for tougher teen driving laws. Delegate William Bronrott sponsored legislation that was enacted last year.

"The legislation strengthened our teen driving laws by restricting cell phone use and also requiring more behind-the-wheel practice time during driver's education," he says. The law also restricts the number of passengers a new teen driver can have in the car.

Bronrott says the rash of teen-driving deaths in his community was a huge wake up call. "I think most parents were very supportive of these laws," he says, adding, "a surprising number of teenagers got involved in helping the bills pass because they recognized that this is the number one threat to their lives as well."

Though it's still too early to measure the effect of these new laws in reducing the teen crash rates in Maryland, a recent study by Johns Hopkins University found that the states with the toughest rules had the fewest teen fatalities. Li-Hui Chen was one of the researchers. "We took the crash involvement rates of 15-year old drivers in those states with graduated licensing laws compared to those without," she says. "We found the average there was 11 percent reduction in crash involvement for 15-year old drivers with graduated license program. So we're encouraging states have comprehensive graduated license programs that include some sort of age restriction, nighttime restriction and passenger restriction."

However, Maryland Delegate William Bronrott notes that tougher laws alone will not solve this problem. "I think that we need parents to play a stronger role in overseeing their children's driving," he says. "We need parents to be involved in making sure that their children are biding by the laws."

Driving expert Timothy Smith agrees. He says parents have to teach their kids safe driving behaviors and set down rules before handing over the car keys to a teenager. He recommends that parents start doing that early on, by setting a good example and being safe and courteous drivers themselves.