Obsidian is an excellent material for the manufacture of stone tools. While there are no tool-quality obsidian sources in Kansas, obsidian is recovered from Kansas archaeological sites. Our recent chemical analysis of 189 samples of obsidian from Kansas archaeological sites demonstrates that obsidian was most commonly used after about 1000 BP, and that sources in New Mexico were used most frequently, but not exclusively. Obsidian sources in Wyoming, Idaho, and Utah also were used, particularly by populations in the northern half of the Kansas, and three samples matched a source area in Hidalgo, Mexico. Finally, there is evidence that specific obsidian source use was a function not only of proximity, but of social relationships as well.