Introduction of predators, parasitoids, and pathogens of Diuraphis noxia (Mordvilko) from Eurasia into the U.S. is a promising approach for reducing the abundance and economic impact of this pest. We summarize the biology of D. noxia natural enemies and the results of foreign exploration by >40 scientists and technicians during 1988–1994. More than 62 exploration trips were made to 17 countries throughout the endemic range of D. noxia. At least 29 species of D. noxia predators and parasitoids in 7 families, as well as 6 species of fungal pathogens, were collected, and >85,000 natural enemies were shipped to the United States for rearing and release. Considerable gaps remain in our understanding of the role of natural enemies in limiting D. noxia abundance in Eurasia. Furthermore, few criteria and techniques are available for choosing among natural enemy species and populations. Nonetheless, these collections provide the basis for a substantial program of natural enemy releases to control D. noxia in the United States.