The CDC Field Epidemiology Manual is the definitive resource for the most up-to-date guidance for epidemiologists and other experts conducting field investigations to address acute public health concerns that require prompt action. This latest edition (an update of the 3rd edition of the popular book Field Epidemiology, edited by Dr. Michael Gregg) offers practical advice to guide investigators through the core elements of field investigations, beginning with initiating operations and ending with developing interventions and communicating findings to the public. The manual also provides special considerations to address challenges that often arise during field investigations, such as addressing legal issues, working with multiple state and federal agencies, navigating a multinational outbreak investigation, and working within an incident management structure. The manual includes updated information on using new tools for field investigations, such as the latest technologies for data collection and management and incorporating data from geographic information systems (GIS). Finally, the manual includes tips for investigations in a wide variety of settings, including healthcare and community congregate settings, and different types of outbreaks, including acute enteric disease outbreaks, those suspected to be related to intentional use of biologic and toxic agents, and outbreaks of suicide, violence, and other forms of injury. The manual is written primarily for epidemiologists who will be conducting field investigations in local, state, federal, or international settings. However, others who contribute to field investigations (e.g., laboratory scientists, lawyers, experts in public policy and communications) will also find the book to be an excellent source of information. The manual is written in an easily readable format, including boxes and bulleted points, to provide greater utility for investigators in the field.