Neutron activation and statistical analyses establish source ascriptions for 201 obsidian artifacts representing Preclassic, Classic, and Postclassic period contexts in the Gulf Coast region of Mexico. Zaragoza-Oyameles, Puebla, and Pico de Orizaba, Veracruz, are the most common sources, but procurement patterns and technology shifted during the archaeological sequence. Comparative information is discussed for all periods, but especially the distribution of Zaragoza-Oyameles obsidian in the Classic period is examined. The distribution network for this obsidian served several regions. The importance of long-distance obsidian distribution for Teotihuac�n is called into question.