If you think in terms of your lifetime, you may ponder that while the hours, minutes, and seconds of a day have remained the same, the amount of information that you have received, let's say, in the 1980s compared with now, 2008, is drastically different. The size of information received in a day now is larger than what you have received in the past years. The information age has also created a wide range of tools, technologies, and techniques that continuously deliver enormous amounts of data, information, and knowledge. We are increasingly flooded with e-mails that routinely have a plethora of documents (in electronic form) that come in all shapes and forms (multimedia etc.) and more sophisticated types of data and information transmissions from sensing and monitoring devices as well. To compound this issue, there are usually no rules or standards, other than common sense, on how or where we should store all this information or knowledge. The bad news is that, with so much of information flow, it is difficult to filter in just the piece that may be needed at the right time. In many cases, we may not be aware where that information may be or if it exists somewhere at all. However, an information glut caused by a combination of pervasive systems and converging technologies may allow us to get useful and, at times, critical information anywhere and at the right time. In the past decade, with the proliferation of the Internet and the World Wide Web, many past and ongoing efforts have tried to improve the movement from text documents and database records to automated reasoning. This process is critical in particular for information sharing. This article provides a background of knowledge management for public health information infrastructure, followed by an illustration of the complexity of knowledge management for health care. We then present an evolving framework for semantic expression that would enable the sharing and exchange of knowledge in public health.