The Mars Global Digital Dune Database provides a comprehensive and quantitative view of the geographic distribution of dune fields from 65° N to 65° S latitude. The database encompasses ~ 550 dune fields, covering ~ 70,000 km2, with an estimated total volume between 3,600 km3 and 13,400 km3. Over 2300 selected Thermal Emission Imaging System (THEMIS) infrared (IR), THEMIS visible (VIS) and Mars Orbiter Camera Narrow Angle (MOC NA) images were used to build the database and are included in the ArcMap and ArcReader versions of the database. An initial data set of THEMIS band 9 spectral range images covering orbits 816-9601 (spanning 02/2002 - 02/2004 and Ls = 0.085º-358.531º) and comprising more than 30,000 images was chosen as the basis for the construction of the database. This provided ~98% nighttime and ~75% daytime areal coverage of Mars planet-wide. Images containing dunes were identified using THV (Interactive THEMIS IR Viewer written in Research Systems Incorporated's (RSI) IDL® software at the USGS in Flagstaff (www.mars-ice.org)). The 100 m/pixel resolution THEMIS IR images were used to locate potential dune features. The higher resolution THEMIS VIS and MOC NA images were used to assign Earth-based dune classifications (McKee, 1979). Where image quality allowed, slipface measurements based on gross dune morphology were digitized to represent primary wind direction responsible for that morphology. Azimuth values were calculated, from crater centroid to dune centroid, for dune fields located within craters. These indicators of wind direction can be compared to the included NASA/Ames Mars general circulation model (GCM) output (Harberle et al., 1999).