Federal Motor Vehicle Safety Standard (FMVSS) No. 213, “Child restraint systems,” specifies performance requirements for child restraint systems (CRSs). The performance of a CRS is evaluated in a simulated frontal impact 48 km/h (30 mph) sled test. The National Highway Traffic Safety Administration (NHTSA) plans to update the FMVSS No. 213 seat assembly to better represent the rear seats of the current 1 vehicle fleet including the geometry, anchorage locations (seat belt, lower anchorages and tether anchorages) and seat foam of rear seats. Limited testing indicates that child restraints in the current market can meet the performance requirements of the current FMVSS No. 213 when evaluated using the updated seat assembly under consideration. Paired comparison analysis of performance measures obtained from CRSs in FMVSS No. 213 compliance tests and those in similar sled tests conducted with the updated seat assembly indicated no significant differences.