With more than 15 sources of obsidian and other lithic materials, the Greater Yellowstone Ecosystem of Montana, Wyoming, and Idaho is one of the richest toolstone regions in northwestern North America. This article introduces a quantitative assessment technique to compare attributes of seven Yellowstone obsidians used by Native Americans over at least 11,000 years. The proposed assessment technique is replicable and adaptable to other regions. This article also analyzes the procurement, use, and distribution of the poorly studied Cougar Creek obsidian. Archaeological research documented Cougar Creek obsidian outcrops, procurement areas, and secondary processing sites. Native Americans acquired the material at surface exposures, as well as occasional trench and pit excavations. There is a significant distance decay reduction in its use, especially when compared with Obsidian Cliff obsidian. Using a weighted z-score analysis, the material attributes of Cougar Creek were compared with those of six regional obsidians to determine the factors involved in their differential use. Based on these rankings, Cougar Creek obsidian experienced low demand and usage due to poor quality and availability. In contrast, due to their high quality, abundance, and aesthetics, Obsidian Cliff and Bear Gulch obsidians were preferred for stone tool production.