X-ray fluorescence measurements of calcium, iron, rubidium, strontium, yttrium and zinc were made on 362 ceramic sherds excavated from the lowland Maya center at Tikal, Guatemala. 12 sample categories include unslipped, polychrome and red slipped ceramics from three cultural periods, the Manik, Imix and Eznab. Also represented are Manik black, Ik polychrome and Imix Tinaja pink. Results of analyses show two prevalent paste compositions, a calcite-tempered type characteristic of unslipped creamics and a calcium-poor, rubidium-rich type typical of Late Classic slipped wares. There is strong overlap in the compositional data among the different ceramic categories. However, despite the similarities, there are measurable differences in the scatter (or variabilities) of these data and in their degrees of overlap. -- AATA