Different governmental agencies have long stored information in restricted-access databases. The advent of online data entry and analysis, and subsequent distribution of data to the public, has created a need for a more rigid set of visualization rules that preserve individual confidentiality. For example, when crime data are disseminated to the public in the form of crime maps via the Internet, law enforcement agencies have to balance between citizens’ rights to know the dangers they face in their neighborhoods, while at the same time preserving the confidentiality rights of the victim. Similarly, in health data it is important to know which “risks” pregnant mothers face in particular neighborhoods, while preserving the actual birth outcomes of women living in those neighborhoods. An ex-graduate student of mine, who currently works for the Office of Public Health (OPH) in Baton Rouge, recently asked for a copy of the original paper on which this chapter is based. Her role in the OPH was as a GIS specialist with a particular emphasis on bioterrorism. The problem that she and the rest of OPH faced was how to publish information on the public’s health on a Web site, while at the same time preserving patient confidentiality.