During three seasons of field research, more than 11,000 obsidian artifacts were excavated from two platform mounds at the Late Classic and Epiclassic period site locus of Santa Cruz Atizapan in the Toluca Valley, Mexico. These artifacts were studied using an attribute analysis, chemical sourcing techniques, and use-wear analysis in order to address questions regarding changes in obsidian acquisition and consumption brought about by the demise of the city of Teotihuacan during the Late Classic. However, due to the nature of the varied analytical approaches and unresolved issues concerning artifact provenience, not all of these objects were analyzed for each approach. Central to this research was an exploration into the availability of local obsidian resources and the degree to which local consumption demands dictated the form and function of imported obsidian artifacts. The results of the research suggest several important patterns of obsidian procurement and consumption at the Santa Cruz Atizapan locus that continued throughout its occupation history: (1) the primary obsidian imported into the site originated at the Ucareo, Michoacan mines, (2) most obsidian objects arrived as finished tools, with only minimal evidence for local manufacture or the importation of large quantities of raw materials, (3) the obsidian tool-kit consisted almost entirely of objects required for performing daily subsistence related tasks and daily ritual activities, (4) most obsidian tools including prismatic blades, were heavily used prior to being discarded; this suggests that they must have been considered something of a rare resource, (5) despite its potential scarcity, access to obsidian tools was not restricted; it occurs in similar patterns in both public and domestic use areas and neither individual tool types nor obsidian sources were found concentrated in specific contexts. The implications of this data are significant. Most importantly, we must reconsider the primacy often attributed to Teotihuacan obsidian trade networks. This case study demonstrates the potential for populations within the Teotihuacan symbiotic region to establish their own procurement systems, even while heavily entrenched in Teotihuacan religious and, presumably, social and politics systems. On a similar but broader interpretive level, we must begin to challenge the notion that Teotihuacan obsidian, particularly the green Sierra de Las Navajas type, was infused with ideological or political symbolism in all cases. Within the southeastern Toluca Valley it clearly was not. Finally, the need to expand this study to other sites in the region, particularly the northern Toluca Valley, is necessary before we can begin to fully understand the regional obsidian networks in place during the Classic period. Our present understanding of Epiclassic period obsidian developments in the region was supported by this research.