The Microbes Within leads students on a guided exploration of the alpha-proteobacterium Wolbachia and challenges them to consider the relevance of this obligate, intracellular symbiont with respect to the evolution of species, insect reproduction and human health. Students are presented with an issue of medical concern and must take advantage of modern-day research to provide persuasive advice to you, the Director of the CDC, through delivery of either a written or oral report. The activity builds upon understanding of basic biology and highlights the impact that one microbe might have on the health of millions worldwide.