Seres Therapeutics has built a proprietary discovery and design platform that enables us to understand the dysbiosis associated with specific diseases, and to rationally design tailored therapies to establish a healthy microbiome. We draw upon the disciplines of systems biology and comparative genomics—as well as our expertise in isolating and characterizing microbes that have been historically difficult to cultivate—to create a new class of therapies aimed at establishing a healthy microbiome. We compare a vast trove of human data from relevant disease states with that from healthy individuals to characterize specific microbiome functions that are disrupted in states of dysbiosis.