No instrumentation specifically designed to measure the topography of a planetary surface has ever been deployed to Jupiter’s moon Io, the most volcanically active body in the Solar System. Available mapping techniques that exist to perform such a task in the absence of the relevant instrumentation include stereo and photoclinometry (shape-from-shading) processing of available Voyager and Galileo imagery. These techniques have been successfully applied to the icy moons of the giant planets, but Io is a much more challenging subject due to its complex and changing photometric behavior and the inherent characteristics of the Ionian surface, as well as the inherent nature of Galileo imagery. This presentation will describe our efforts to produce the best quality digital elevation models (DEMs) of Io to date using both techniques, to control these DEMs using Galileo limb profiles (the only true topographic ground data available), and to merge and mosaic the DEMs to form a global topographic map of Io. While our investigation has focused almost entirely on refining our mapping technique, future science objectives that can be addressed by the data in the DEMs will be discussed.