NIOSH and the Occupational Safety and Health Administration (OSHA) share responsibility for overseeing respiratory protection in the workplace and have established regulations for this purpose. Specifically, NIOSH has issued regulations which define respirator testing and certification. OSHA has issued regulations which define conditions under which employers are required to maintain respiratory protection programs in general industry, shipyards, marine terminals, and construction. In 2005, NIOSH contracted with the Institute of Medicine (IOM) to study the NIOSH-sponsored Anthrotech study along with its supporting information and reports, and to examine and report on the adequacy and relevance of the study protocol, the analyses conducted, the resulting anthropometric dataset, and the appropriateness of the respirator fit-test panels derived from the new dataset. This report focuses on the establishment of the scientific base required for certification standards of respirators, not their use in the workplace. This report describes and analyzes the anthropometric measurements performed by Anthrotech for its NIOSH-sponsored study. This report looks at the survey methods used by Anthrotech in the study, and examines how Anthrotech analyzed its data to derive fit-test panels and suggests some ways that analysis could be improved. This report discusses future directions, pointing toward further analyses of the data and offers suggestions for moving from research to practice.