Publish/Subscribe is a messaging paradigm where senders (publishers) of messages are not programmed to send their messages to specific receivers (subscribers). Rather, published messages are characterized into classes, without knowledge of what (if any) subscribers there may be. Subscribers express interest in one or more classes, and only receive messages that are of interest, without knowledge of what (if any) publishers there are. In this book, a Context-aware Model for Public Health Service delivery was developed and implemented through a Publish/Subscribe Information System in which users can subscribe to topics of interest in the Public Health domain and have it published to them on their mobile phones as well as on their personal Computers. It was achieved via the following methods: review of related works, system evaluation, model formulation, development and implementation of the model to verify our assumptions. The materials used to implement this model are the Microsoft Visual Studio, C#, SQL Server, Ozeki Message Server, a few computer systems (one to serve as the server and others as client) and Two Multimedia Phones. The eGranary was used as the information database.