A novel head-tracking technique for a full-color stereoscopic video display system is presented. Using this head-tracking system, the stereoscopic area is increased by a factor of three and stabilized stereoscopic images are observed. Two kinds of large-size rear-projection stereoscopic display systems that do not require special glasses are proposed. Experimental tests, confirming the effectiveness of the proposed systems, are described. By incorporating these techniques into visual communication systems, such as TV telephone systems, video conference systems, or virtual reality systems, a very natural and accurate depth sensation which cannot be obtained by conventional systems that require the viewer to wear special glasses may be possible.>