Parasitic relationships are among the most common yet complex associations found in nature. This book makes an important contribution toward integrating parasitology into the mainstream of ecological and evolutionary studies. It delves into a number of key questions: to what extent are parasite-host interactions an escalating evolutionary conflict and, conversely, to what extent has evolution modified this process to facilitate co-existence? The first section of the book deals with whole organisms and populations, since the effects of parasitism are dependent on the densities and distributions of hosts and parasites. The next section considers special cases, such as herbivores and plants. The third part is devoted to physiological and immunological aspects, and the book concludes with an overview from the perspectives of ecology, evolution, and physiology. The work will interest ecologists, evolutionary biologists, parasitologists, entomologists, and epidemiologists.