Effective communication between public health agencies and their external stakeholders is vital to the agencies, as well as to those they serve. Agency leaders must obtain information from stakeholders and provide information to them. A process is described whereby agencies can systematically obtain necessary information from external stakeholders, and three of the most important forms of communications are described through which an agency provides information to stakeholders: promotion of the agency, advocacy, and social marketing. Barriers to effective communication of the interpersonal, personality, organizational, operational, skill/knowledge, attitude, and nature-of-information types are described, and guidelines are provided for minimizing the impact of these barriers.