Many environmental processes are influenced, if not controlled, by microbial action and it is becoming increasingly important to develop an understanding of microbial roles in geochemistry. Focussing on environmental radioactivity, it may initially be questioned whether understanding these interactions will really be of any practical or predictive benefit? Are microbial effects on radionuclides really that important? This book goes some way to answering these questions, bringing together a representation of the state of the art research investigating these interactions and the extent to which they affect or can be used to control radioactive elements. The basic principles and fundamental mechanisms by which microbes and radionuclides interact are outlined, the methodology described, potential microbial influences on waste repositories examined, direct and indirect effects on transport both on local and global scales considered and potential technological applications identified. Here, we briefly consider these topics and explain why this emerging field will be of increasing importance in the future.