The information in the User Guide will help the reader: Understand the human health risk factors associated with extreme heat events; Recognize key vulnerability factors in specific populations; Understand options and opportunities for managing heat-health risk factors, for example, by tailoring and targeting health protective actions to at-risk individuals; Provide information for health administrators and health care workers to identify opportunities for integrating activities to reduce heat-health risks into work and planning; Facilitate the exchange of knowledge regarding extreme heat and health among health administrators, health care workers and the public.