Make sure he's really ready for them. Kids need coordination, balance, and good judgment.
Read the instructions. Parents often skip this, but it's crucial, says John Purvis, M.D., at the American Academy of Orthopaedic Surgeons. Heelys.com has how-to videos and in-store lessons.
Insist on protective gear, like a helmet and wrist pads. Heelys may seem just like fancy sneakers, but you should think of them as skates.