Despite mandatory-use laws in all states, many parents still don't buckle their kids into child safety seats correctly - or at all. If they did, 500 young lives could be saved a year.

Better Homes and Gardens, a Meredith magazine, offers tips on what parents should know about child seats and restraint laws."Failing to secure your child is really a form of child abuse," says Larry Michael Ellis, director of the highway safety program in Tennessee, the first state to pass a restraint law. All 50 states have such laws today.

According to the National Highway Safety Administration, child safety seats saved at least 200 lives last year and prevented 28,000 serious injuries. If all parents correctly used child seats, at least 500 lives a year would be saved.

But many parents still don't comply with their state's laws, or they use the restraints incorrectly. Here's how parents can protect their children:

- Child seats not only help prevent a child from being thrown about the car. They also help soften the impact of a crash and distribute the forces more evenly over the child's fragile body.

- Holding a child in one's arms isn't safe. According to Carol Dingledy, of Cosco Inc., simulated-crash tests at the University of Michigan demonstrated that adults were unable to hold onto a dummy "baby" at 15 mph. And at 30 mph, the force of the accident can cause a child to be crushed between an adult and the dashboard or seat back.

- Most experts agree that some form of safety seat should be used until the child is large enough to be comfortably and safely buckled up by a car's own seat belt. And, of course, parents must comply with their state law's guidelines. Children's safety seat regulations vary in terms of age (typically, up to age 4 or 5), weight and height. Check state statutes carefully.

- A car safety seat holds a child in an erect or semi-reclined position comfortably, with a shield or harness securing the child just as a seat belt does. All seats manufactured since 1981 must meet federal guidelines, but there are substantial differences between models. Prices run from $20 to almost $100, depending on the type of seat, quality and features.

- Infant-only seats work for babies up to 17 to 20 pounds. These seats rest the child in a semi-reclined position and must always face to the rear. (A baby's back is much better able to absorb the impact of a crash.) Be sure the seat has an FMVSS 213 label on it.

- Don't expect infant carriers to do double-duty in the automobile, even for that first trip home from the hospital. They are not designed to buckle into a car, nor do they have the restraints needed to protect a baby in a collision.

- Convertible car safety seats are today's most popular design because they adapt easily from birth until about age 4 or until the child reaches about 40 pounds or 40 inches. The seats face backward for small infants, then forward, once the child reaches 17 to 20 pounds. That gives increasingly active children more of a view, helps keep them satisfied and less likely to fuss.

- Auto booster seats provide added support to children who have outgrown convertible seats. Reversible boosters provide two heights to accommodate a child's growth. Most boosters use some sort of shield to reinforce the car's own safety belt. Continue to use a booster until the child is tall enough so that the midpoint of his or her head reaches the top of the seat back.