In 2003, the U.S. Dept. of Ag. initiated the Program of Research on the Econ. of Invasive Species Mgmt. (PREISM) to examine the economics of managing invasive pests in increasingly global ag. markets. Invasive species are defined to include any vertebrate, invertebrate, weed, fungus, plant disease, livestock disease, or other organism that meets the following criteria: Is non-native, alien, or exotic to the ecosystem where it exists or potentially could be introduced -- incl. ag., range, and forest ecosystems; and when introduced, causes, or is likely to cause, economic or environ. harm. PREISM¿s will build a high-quality, multidisciplinary research program to provide analytically based principles, guidelines, and criteria for invasive species policy. Ill.