Only buy a helmet that meets the Consumer Product Safety Commission (CPSC) [2] standards (look for the sticker in the helmet signifying that the helmet passes the standard). The CPSC standard:
Ensures
that bike helmets will adequately protect the head and that chin straps
will be strong enough to prevent the helmet from coming off in a crash,
collision or fall.
Requires that helmets intended for children up to age five cover more of the head to provide added protection to the more fragile areas of a young child's skull.
Let
your child help pick out the helmet. Helmets now come in a variety of
colors and patterns, and by involving your child in the selection
process, you will increase the chances that your child to wear the
helmet.
Have your child try on the helmet in the store, to make sure you get the right size.
Helmets come in child and adult sizes. Don't automatically buy a child size helmet; many children wear adult size helmets. Measure the circumference of your child's head.
To
save money, try to get a helmet included in the deal when you buy your
child a bike. This is probably easier to accomplish if buying from a
bike shop rather than a large department store.
Remember: Helmets should be replaced if they have been involved in a crash.
Links:
[1] http://www.safechild.net/
[2] http://www.cpsc.gov/talk.html