In this report we attempt to answer the question: which measurement system did the Late Classic Maya use to build their buildings? Measurements were collected from ten buildings at three Puuc style archaeological sites: Uxmal, Kabah and Chichén Itzá, which date about A.D. 750-1000. The tentative results of the study suggest the Maya employed a measurement system involving what we are calling a zapal, which was 147 ± 5 cm long. A zapal was divided into 16 units, kab, of 9 xóot’ each, or 9 units, oc, of 16 xóot’ each. Thus, there were two alternative ways of grouping the 144 xóot’ that made up each zapal. An examination of the linguistic and ethnohistoric data reveals nothing to contradict the notion that such a measuring system was present among the ancient Maya, and that multiples of 3, 4, and 12 are involved.