SUMMARY: This final rule amends the Federal motor vehicle safety standard for child restraint systems to expand its applicability to child restraints sold for children weighing up to 36 kilograms (kg) (80 pounds (lb)). This rule also amends the standard to incorporate use of a Hybrid III 10-year-old child test dummy (HIII?C10C)@ weighing 35 kg (78 lb)@ in compliance tests of child restraints newly subject to the standard. In a companion document published elsewhere in this issue of the Federal Register@ NHTSA is adding specifications and qualification requirements for the HIII?C10C to our regulation for anthropomorphic test devices. This rulemaking establishes performance and other requirements for child restraint systems heretofore not regulated by a safety standard@ i.e.@ child restraints manufactured for children weighing 65 to 80 lb.