A set of 296 obsidian artifacts from the lakes area of the Department of Peten, Guatemala, has been provenanced by x-ray fluorescence and neutron activation analysis. The obsidians come from socioeconomic contexts (primarily rural/domestic) and time periodsmfrom the middle Preclassic period, ca. 800 BC, up to the time of Spanish contact, 1525 ADmthat have been poorly represented in previous Lowland provenance studies. Thus they provide new data on the acquisition and distribution of this important nonlocal commodity in the Maya Lowlands.