Obsidian studies in the greater American Southwest have come of age. No longer does the region lag behind other adjoining regions both in the understanding of source provenance and the integración of obsidian source studies into regional designs. Most of the archaeological obsidian sources discussed here were originally presented in semi-quantitative form in this journal in 1988 (Shackley 1988a). The purpose here is to present that same data in broadly useable quantitative form calibrated to international standards, update the source descriptions when appropriate, and, finally, present data on a few new sources recently located. This is a necessary step to continue the momentum of obsidian studies in the region and make the information available to all. Finally, some discussion is directed toward the archaeological utility of obsidian studies in the region.