Host-microbe interactions shape each other’s physiology, ecology, and evolution. Human health, for instance, can be strongly influenced by the symbiotic microbial community. The impact of these interactions extends to the ecology of terrestrial and aquatic ecosystems. This is an expanding field of research in biology and there is a current need to summarize and integrate the knowledge that is being generated, and to extrapolate general principles to be incorporated in future innovative research projects. This Summer School aims at training the next generations of researchers in host-microbe symbioses.