A collaborative program between the Field Museum, the National Cancer Institute, and the National Biodiversity Institute (INBio) in Costa Rica has been developed to initiate a rigorous bioprospecting survey of the macrofungi of the Guanacaste Region in northwestern Costa Rica. This project is closely linked with the PI's current program that focuses on the macrofungi of Costa Rican oak forests that is being undertaken in collaboration with the University of Costa Rica. Funds requested in this new proposal will be used to support a parataxonomist in the Guanacaste Conservation Area and a curator at INBio to collect, take the necessary morphological descriptions, make spore prints, do initial identifications and send the material to the Field Museum for culturing to generate prospecting samples. Duplicate specimens and cultures will remain in Costa Rica to further develop the mycological herbarium at the University of Costa Rica and begin the mycological herbarium and fungus culture collection at INBio. The part-time grant supported technician at the Field Museum will undertake the initial culturing, work with the PI to make, or confirm, identifications of each sample, and help train the INBio curator when he visits the Field Museum. The PI will be responsible for the administration and coordination of the project, training of Costa Rican personnel, identification of samples, and selection of material to be sent to NCI for screening. Samples will then be sent to the Natural Products Branch of the National Cancer Institute for screening for anticancer and AIDS-antiviral activity. Letters of agreement between these three institutions have been developed. The three major ecological zones in the Guanacaste Conservation Area (GCA), dry forest, cloud forest, and rain forest, cover approximately 36 different habitats and are estimated to be home to 60% of Costa Rica's biodiversity. Based on our current work in Costa Rica, many new species of fungi await to be discovered. Thus the possibility of including novel fungi in our screening program is very high. In addition to housing incredible biodiversity in a relatively small area (120,000 ha), the GCA is an ideal place to carry out our planned project because much of the necessary infrastructure is already in place. The research and training being undertaken in this projects designed to build upon the developing fungal programs in Costa Rica in general, on INBio's national inventory and efforts toward non-damaging biodiversity development, and on the specific All Taxa Biodiversity Inventory (ATBI) of the GCA in particular. Fungi are an integral part of the developing activities surrounding the ATBI and this proposal is designed to be part of these activities. Finally, an important component to this program will be the further development of mycological expertise in Costa Rica through training and building of infrastructure. These developmental aspects are in consort with the PI's parent grant, which has a major infrastructure building component.