The George Mason University Center for Climate Change Communications conducted research on how to effectively communicate the public health implications of climate change to create a communication primer for public health professionals. In a survey conducted with local public health officials in 2008, over half of the nation's public health departments reported they were already experiencing health effects from climate change, yet fewer than 10% were taking steps to educate members of their community about the risks. With the help of this new primer, public health professionals can better communicate with the public about the changing climate and the role it will play in the publics health. This primer was developed to help public health professionals communicate the health implications of climate change to the public, to policy makers, and to other professionals whose work is or will be affected by climate change. Specifically, this primer is organized into three sections so as to answer the following questions: WHY should public health professionals communicate about climate change? With WHOM should public health professionals communicate about climate change? HOW should public health professionals communicate so as to be most effective?