Presentations were given by representatives of government agencies, private laboratories, scientific experts, and rescue organizations. Participants explored the expertise and responsibilities of the Federal Bureau of Investigation, National Domestic Preparedness Office, the Interagency Board for Standardization and Management, and others. The need for additional research, guidelines, and standards were identified in the following areas: exposure limits and technology for assessing chemical and/or biological concentrations of response scenarios; improved chemical and/or biological detection and monitoring capabilities; reliable information with which to define acute compared with chronic doses and their immediate and long-term health effects; and the applicability of military data. Discussions emphasized the importance of protecting first responders to a chemical and/ or biological incident; the level of protection was noted to vary among the diverse groups of emergency responders. The workshop identified immediate-responder needs in a number of areas, including National Institute of Occupational Safety and Health certification of various types of respiratory-protection equipment, technical assistance in the selection of such equipment, and alternatives to self-contained breathing apparatus for certain threat scenarios. The workshop closed with the assurance that the National Institute of Occupational Safety and Health, the Department of Defense, and the Occupational Safety and Health Administration would continue working with partners to investigate the funding and collaborations required to develop certification standards for chemical and/or biological respiratory equipment and the other issues raised in the Workshop. Appended plenary-speaker abstracts and biographies, a list of registrants and attendees, and a list of the names and properties of the chemical and biological agents of concern