This book provides a series of reports from the 1st International Conference on Model Hosts. This first of its kind meeting focused on invertebrate, vertebrate and amoeboid systems used for the study of host-pathogen interactions, virulence and immunity, as well as on the relevance of these pathogenesis systems and mammalian models. Importantly, a common, fundamental set of molecular mechanisms is employed by a significant number of microbial pathogens against a widely divergent array of metazoan hosts. Moreover, the evolutionarily conserved immune responses of these model hosts have contributed important insights to our understanding of the innate immune response of mammals.