The Vegetation/Ecosystem Modeling and Analysis Project (VEMAP) is an ongoing multiinstitutional, international effort addressing the response of biogeography and biogeochemistry to environmental variability in climate and other drivers in both space and time domains. The objectives of VEMAP are the intercomparison of biogeochemistry models and vegetation type distribution models (biogeography models) and determination of their sensitivity to changing climate, elevated atmospheric carbon dioxide concentrations, and other sources of altered forcing. The VEMAP climate data set includes daily, monthly, and annual climate data for the conterminous U.S. including maximum, minimum, and mean temperature, precipitation, solar radiation, and humidity. Seasonal mean surface wind speed is also provided. The monthly, seasonal, and annual data are long-term climatological means and are on the CDROM and FTP site under the subdirectory /monthly. Annual averages are simple means of the 12 monthly fluxes. The daily set presents a "characteristic year" in which monthly averages or accumulations of the daily values match the long-term monthly climatology but where the daily series has variances and covariances characteristic of a station's weather record. The daily data are on the CDROM and FTP site in the subdirectory /daily. A complete users guide to the VEMAP Phase I database which includes more information about this data set can be found at ftp://daac.ornl.gov/data/vemap-1/comp/Phase_1_User_Guide.pdf. ORNL DAAC maintains additional information associated with the VEMAP Project. Data Citation: This data set should be cited as follows: Kittel, T. G. F., N. A. Rosenbloom, T. H. Painter, D. S. Schimel, H. H. Fisher, A. Grimsdell, VEMAP Participants, C. Daly, and E. R. Hunt, Jr. 2002. VEMAP Phase I Database, revised. Available on-line from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.