Schistosomiasis, filariasis, and geohelminth infections still cause untold misery, along with their protistan counterparts such as leishmaniasis and amebiasis, especially in the tropics. But these infectious diseases also have inspired generations of parasitologists to apply their time, talents, and intellectual resources to find cures, or develop control methods, and thus provide relief from the economic and social burdens caused by parasitic organisms. In their quests to develop treatment and control technologies, parasitologists have indeed produced some major successes over the past century, but in the process they also have made conceptual contributions that might arguably be described as metaparasitology, an intellectual realm that includes the rules for pursuing the discipline. Although it may not always have been their intent, parasitologists have done research that in turn shapes the ideas about interactions between hosts and parasites.