This is a comprehensive review that bridges the gap between evolutionary biologists and parasitologists. Some chapters deal with conceptual issues, such as demography or sexual selection; others present the nuts-and-bolts information about parasites themselves and methods used to study them. Because birds have figured prominently in much evolutionary work on host-parasite interactions, the emphasis is on avian systems, but other systems are included where relevant. It will be an invaluable reference for students and researchers from a wide range of disciplines interested in understanding host-parasite interactions.