Increasing seat belt use is one of the most effective and least costly ways of reducing the lives lost and injuries incurred on the nation's highways each year, yet about one in four drivers and front-seat passengers continues to ride unbuckled. The Transportation Research Board, in response to a congressional request for a study to examine the potential of in-vehicle technologies to increase belt use, formed a panel of 12 experts having expertise in the areas of automotive engineering, design, and regulation; traffic safety and injury prevention; human factors; survey research methods; economics; and technology education and consumer interest. This panel, named the Committee for the Safety Belt Technology Study, examined the potential benefits of technologies designed to increase belt use, determined how drivers view the acceptability of the technologies, and considered whether legislative or regulatory actions are necessary to enable their installation on passenger vehicles. The National Highway Traffic Safety Administration (NHTSA), the study sponsor, funded and conducted interviews and focus groups of samples of different belt user groups to learn more about the potential effectiveness and acceptability of technologies ranging from seat belt reminder systems to more aggressive interlock systems, and provided the information collected to the study committee. The committee also supplemented its expertise by holding its second meeting in Dearborn, Michigan, where it met in proprietary sessions with several of the major automobile manufacturers, a key supplier, and a small business inventor of a shifter interlock system to learn of planned new seat belt use technologies as well as about company data concerning their effectiveness and acceptability. The committee's findings and recommendations are presented in this five-chapter report.