Entomopathogenic nematodes in the genera Heterorhabditis and Steinernema are potent biological control agents that have been commercialized widely for control of economically important insect pests. This chapter describes the foraging and infection behavior of nematodes and the production technology, formulation, application technology, and commercialization of entomopathogenic nematodes. The chapter considers the factors affecting the efficacy of nematodes in integrated pest management and methods to improve their efficacy. Finally, the chapter looks ahead to future research trends in this area.