Protecting the population against the effects of a bioterrorism attack is one of the most daunting tasks facing government officials. Some of the information required to make informed decisions is highly technical, and even the technical experts do not agree about many of the details or issues involved. This primer is written for the non-technical policymaker and is designed to assist him or her in reaching important decisions regarding how best to help provide early warning of a biological attack. The authors also present the results of an extensive statistical study that examined the utility of a system-of-systems approach to identifying a bioattack. Using a hypothetical system-of-systems that obtains medically relevant data from 10 sources, the study reaches several conclusions. Among them, that policymakers: - Reassess efforts currently underway that attempt to capture data from absenteeism reporting, OTC pharmacy sales and medical claims reporting, because their value added may not be worth the cost. - Increase efforts to collect medical data. These efforts would include, but not be limited to, capturing data from doctors' offices and ER visits, as well as expanded veterinary and agricultural surveillance. Increase data collection from medical website visits and nurse helplines. - Reassess current plans to significantly increase the number of biosensors deployed as part of both the BioWatch and Guardian programs. Finally, the authors propose testing an innovative approach to monitoring for the presence of biological pathogens. They recommend that the 23,500-strong workforce of law enforcement officers, firefighters and mail carriers in Washington, D.C., be monitored daily by thermal imagers for increases in body temperature. This workforce is uniformly distributed throughout the city and is both inside and outside of buildings, thus avoiding some of the problems cited with the current use of stationary sensor systems.