Book excerpt: The Institute of Medicine's Roundtable on Population Health Improvement brings together individuals and organizations that represent different sectors in a dialogue about what is needed to improve population health. On September 22, 2014, the roundtable held a workshop to discuss some of the science of health communication, audiences, and messaging, and to explore what it will take to generate widespread awareness, acceptance, and action to improve health, including through the entertainment media, the news media, and social media. This report summarizes the presentations and discussion of the workshop.