Wheat is grown on more than 200 million hectares worldwide and is a source of food and livelihoods for hundreds of millions in developing countries. Until the advent of science-based agriculture, world wheat harvests were held hostage by rapidly evolving fungal pathogens, among the most damaging of which were the rusts. Modern breeding, combined with the free international exchange of experimental wheat lines, resulted in the development and wide dispersion of wheat varieties able to resist the rusts for several decades. Many developing country farmers cannot afford fungicides, so resistant wheat varieties constitute a major safeguard of their food security. However, a new strain of stem rust has emerged in eastern Africa that is virulent to most wheat varieties currently sown. Its spread is likely, and a major stem rust epidemic could reduce world wheat production lOpercent-a loss of 60 million tons of grain worth US$ 9 billion or more, as grain prices rise due to shortages. This proposal is for a worldwide consortium to develop and disseminate new, high-yielding, resistant varieties and set in place warning systems, international testing networks, trained staff, and partnerships to detect and counter new, virulent strains of wheat pathogens.