If knowledge of environmental conditions associated with naturally occurring entomopathogenic nematode populations is sufficient, then ecosystem management practices might be designed to encourage presence and persistence of these biological control agents and long-term pest suppression. We have conducted our research on naturally occurring entomopathogenic nematode populations in two Ohio ecosystems, a vegetable production area with a diverse mixture of crops, and insect pests, and high organic matter soils, and golf course turf that varies in the intensity of turf management. Endemic steinernematid or heterorhabditid populations have been recovered from both and related to the soil and other habitat characteristics by a multivariate statistical analysis on soil biotic and abiotic attributes. The relative importance of these habitat characteristics in explaining presence and abundance of endemic entomopathogenic nematode populations varies according to the soil, species of nematodes and land management practices used.