Risk communication manages how a potential hazard is represented to multiple audiences. This book details risk communication literature, its strategies, and the research evidence for what happens in a risk analysis when data is unavailable due to randomness or incompleteness. It examines these issues in the context of nanotechnology, as a case study of an emerging technology area that presents risk communication challenges. Inexpert audiences may not assess risk by using equations but rather by weighing a combination of scientific, social, and emotional factors. Understanding risk perceptions and communicating risks related to nanotechnology can pose special issues. For many people, especially people who are unaware, unfamiliar and/or uncomfortable with science, the topic of nanotechnology can be difficult to understand. In addition, for some people, nanotechnology evokes concerns related to the environment, health, safety, or other societal issues. Nanotechnology's interface with biotechnology and other sciences and the complexity of nanoscience applications, present numerous challenges to risk communicators.