Obsidian gives the archaeologist the unique opportunity to study the direction, intensity, and extent of ancient exchange through source analysis, and can also provide the requisite chronological framework for a diachronic perspective on exchange. This report presents the preliminary results of a detailed source and hydration dating study of a large sample of obsidian artifacts collected from seven sites in the Oaxaca region. It is one project of a series undertaken by the Missouri University Research Reactor lab aimed at determining if the technique of combining sourcing and hydration dating is as feasible in practice as it is in theory. The next two parts relate to methodology, with the first describing a new, high-precision, rapid method of instrumental neutron activation analysis for sourcing obsidian. The second part presents the method used to date the obsidian artifacts by hydration measurements, along with the results obtained so far and several problems encountered during the research. A discussion of the acquisition patterns revealed by the source analysis of the Oaxacan materials, and compared to previously proposed models of exchange, concludes the text.