This chapter presents a case study on The Discovery of Vaccines using a discovery engineering process. In this lesson, students read about Dr. Edward Jenner’s use of cowpox to vaccinate people against smallpox. Students review different viral diseases and determine what vaccines are available to combat them and use this information to research and identify common viral diseases and discuss which of these need vaccine development. Finally, students select one disease and consider the steps that are needed to develop, test, and/or improve a vaccine. This lesson may be taught during a unit on viruses or disease for beginner biology courses. A list of materials, teacher background information, teacher notes, references, resources, assessments, and standards are provided. This book selection also includes the Table of Contents, About the Authors, Acknowledgments, Introduction, and Index.