The NASA Landsat Data Collection (NLDC) is a compilation of Landsat multispectral scanner (MSS) scenes and Landsat thematic mapper (TM) scenes. This compilation of scenes represents data collections from four distinct projects including: (1) the Global Change Landsat Data Collection (GCLDC);(2) the Humid Tropical Forest Project (HTFP) collection of source scenes and products; (3) a collection of data from the Committee on Environment and Natural Resources Research [formerly the Committee on Earth and Environmental Sciences (CEES)] that is historically referred to as the CEES collection; and (4) ongoing Landsat data purchases by NASA-funded investigators, starting with the 1996 fiscal year. The NLDC scenes have been screened for cloud cover and band quality resulting in a high grade,high quality data compilation. The GCLDC collection contains Landsat TM scenes that were purchased by NASA from Space Imaging, formerly the Earth Observation Satellite Company,under a special agreement to promote the use of shared data in global change research. The HTFP, the largest component of NASA's Landsat Pathfinder Program, contains Landsat MSS and TM scenes collected over the past 20 years. The goal of the HTFP is to globally map deforestation in the humid tropical forests. The CEES collection is the result of an effort to coordinate data needs among several Federal agencies (e.g.,Environmental Protection Agency, Department of the Interior agencies, National Oceanic and Atmospheric Administration, Department of Defense). These Landsat TM scenes were collected for a variety of research projects. Ongoing NASA purchases of Landsat TM data support NASA scientists and their affiliated researchers in programs and projects including the NASA Research and Analysis Program; the Global Land Cover Test Sites Project; the HTFP, the International Biosphere-Geosphere Programme, the NASA Applications Program; and the Landsat-7 Science Team.