The National Transportation Safety Board examined the effect of not using an age-appropriate restraint system and the effect of not using a restraint system properly on injury severity. The Safety Board found that improperly restrained children in an age-appropriate restraint system sustained a greater proportion of moderate or worse (AIS 2-6) injuries than properly restrained children who were in the wrong restraint for their size. This was true particularly for infants and small children who were likely to be in a child restraint system. The study underscores the importance of proper use of restraint systems and makes recommendations for improvements in restraint system designs for children.