In 2013, the National Institutes of Health (NIH) and the Food and Drug Administration (FDA) held a workshop to determine the risks and benefits associated with the experimental use of fecal microbial transplants to treat Clostridium difficile and other gastroenterological disorders. By focusing on the proceedings of the NIH–FDA workshop on the treatment of the human microbiome, the question of how medicine colonizes human bodies through microbial transplants raises questions about what an individual body is, how determinative of human health the microbiome is, and what the limits of molecular biomedicine are when the microbiome is taken into consideration. In the workshop presentations and discussion of this emerging treatment, experts used ideas about the normal, regular, and standard to move between scales of bodily analysis, from the microbial to the body politic, demonstrating how the individual and society are deeply influenced by the unruly community of microbial symbiotes that humans host.