The risk communication literature discusses a number of principles regarding how best to communicate risk. This chapter focuses on principles of risk communication that are within the purview of those who are communicating risk: the principles related to the risk communication process, risk communication presentation, and risk comparison. Unless specifically noted, these principles apply equally to care, consensus, and crisis communication. The principles that have been developed through years of study can be distilled into two maxims: know the audience and know the situation. The risk communicator should know about the needs of the audience (what they want to know and what the risk communicator needs to tell them to help deal with the risk), the manner/mode of receipt the information by the audience, and what the risk communicator can do within certain constraints.