The Missouri Botanical Garden (MBG), in collaboration with IUCN-The World Conservation Union, conducted Red List assessments for more than 1,800 target plant taxa (species, subspecies, and varieties) in the Eastern Arc Mountains and Coastal Forests (EACF) Biodiversity Hotspot of Tanzania and Kenya. Comprehensive, geo-referenced collection data for each of the species were the primary basis for the plant Red List. Project personnel collaborated with staff members and researchers at the East African Herbarium of the National Museums of Kenya, the National Herbarium of Tanzania, the University of Dar es Salaam Herbarium, and the Royal Botanic Gardens, Kew, to collate all existing specimen data in MBG’s TROPICOS database. GIS analysis of distributional patterns and apparent gaps provided the basis for planning targeted inventory expeditions to poorly known parts of the Hotspot. The Species Information Service of IUCN analyzed distributional and population data, and the project will publish Red List assessments electronically and in hard copy. Close contact and collaboration with key planners and decision makers assure that these assessments will be used in design and implementation of conservation policies based on comprehensive, verified scientific data.