Invertebrate hosts and their diverse pathogens and parasites provide an opportunity to understand both ecological and evolutionary dynamics of species interactions. Invertebrates are well-suited to such studies for a number of reasons, including rapid generation times, amenability to experimental and molecular approaches, and, increasingly, the availability of genomic data. As a result, there has been a dramatic increase in studies on a diverse suite of invertebrate host-parasite systems, improving our understanding of host-parasite processes at genetic, genomic, population and community levels. In this session, speakers will discuss projects coupling genetic, ecological and evolutionary analyses to study aquatic and terrestrial invertebrates, and their viral, bacterial, fungal and protozoan parasites. The session will highlight how these systems are being used in novel ways to address interesting ecological questions. First, though molecular biologists have been studying immune pathways for decades, only recently have researchers begun to ask how the genes underlying immune responses influence ecological host-parasite interactions. Second, well known model systems, such as migrating monarch butterflies, are now being used to address challenging questions in host-parasite systems, such as the evolution of virulence. The genomes of many organisms featured in this session have been recently sequenced, and information derived from the genomes is already shaping host-parasite research. Recent annotations of the Daphnia, pea aphid, and bee genomes, as well as the genomes of some pathogens, have provided tools to investigate host-parasite interactions at the molecular level. These genetic analyses now inform experimental studies on host and parasite variation in susceptibility and virulence and thus demonstrate how genomics can inform ecology. The research of the invited speakers spans the breadth of the field, from studies of gene expression to studies of the affects of environmental variables on population level processes. Talks will be arranged to highlight this spectrum. The session will start with research utilizing genetic and genomic tools to study host responses to parasites (Evans, Gerardo, Little), will then move into questions of how genetic variation shapes eco-evolutionary dynamics (Duffy, de Roode) and will finish with talks focusing on the population and community ecology of parasitism (Altizer, Dwyer). Each transition point is bridged by talks on similar systems. Little and Duffy will present different perspectives on Daphnia-parasite interactions, and de Roode and Altizer will present research in the monarch-parasite system. Three slots are currently available for contributed abstracts, which we hope would be distributed across the different research foci.