From 1999 to 2002, 32% fewer US children between 9 and 36.4 kg (20-80 lb) were restrained inappropriately in seat belts and the most prevalent form of restraint shifted from seat belts to child restraints with harnesses. There was a significant increase in the use of combination child restraint/booster seats with harnesses by children 9.1-18.1 kg (20-40 lb). Among children weighing 14.1-18.1 kg (31-40 lb), the inappropriate use of seat belts and shield boosters decreased. Among children weighing 18.6-27.2 kg (41-60 lb), the use of belt-positioning booster seats increased while the inappropriate use of seat belts decreased. Of note, by the end of 2002, 27% of children weighing between 18.6 and 22.7 kg (41-50 lb) were restrained in child restraints with harnesses. These children were of weights typically above the manufacturer's recommended limit. Despite progress, substantial inappropriate restraint still remains and continued investment in outreach efforts is necessary. The risk of injury for heavier children in child restraints with harnesses should be monitored.