The population dynamics of a general three-species, three-trophic-level exploitational system are explored. The conclusions pertaining to three levels are much the same as those for two. Exploitation is defined as one species using another to satisfy its reproductive requirements while the other suffers reproductive depression because of the interaction. Exploitation is the only interspecific interaction assumed to exist in the system. Other assumptions of the theory include: (a) it is possible to construct a first-order partial, nonlinear, differential equation for each species which will predict the population dynamics of that species (such equations do not exist today because of our ignorance); (b) carnivores exploit herbivores, herbivores exploit plants; (c) both herbivores and plants exhibit intraspecific competition at high densities and intraspecific mutualism at low densities. The mutualism may be only technical and requires only that the victim's predators exert a diminishing effect on each victi...