Considerable progress has been made in recent years in unravelling the complexities of the snail-parasite relationship. The chapters in this work cover many different aspects, including ecology, parasite transmission, parasite interactions, evolutionary biology, molecular systematics, and snail defense systems; emphasizing the topical nature of this important area of parasite biology. Many new techniques are now used to investigate the intricacies of host-parasite relationships. Genome and post-genomic studies, such as the schistosome genome project, are set to revolutionize parasite biology and unravel molluscan genomes.