Provenience analysis of a small sample of obsidian artifacts from Isla Cerritos, a Terminal Classic/Early Postclassic Itzá trading port on the north coast of Yucatán, indicates a wide range of raw material sources from Central Mexico to the Guatemalan Highlands. The overwhelming predominance of Central Mexican obsidian reinforces the notion that Isla Cerritos was the main trading port of Chichén Itzá. The analysis also provides an indirect approximation of the Itzá obsidian trade networks, which were heavily reliant on sources that may have been under the control of the Toltec capital at Tula.