Survey and excavations of mounds on the outskirts of the site of Pacbitun in western Belize provide insights into the ancient Maya settlement pattern at this medium-sized regional center. This research employed two methods: analysis of structural remains from four separate 1000 m transect surveys, and a subsequent complete (100%) survey of intervening and adjacent quadrant areas. The overlap of quadrant zones with portions of the transect units permits an examination of the accuracy of transect surveys. Excavation of a 22% sample of all identified mounds provides chronological and functional information. An estimate of 200 persons for the resident elite population of the Epicenter of Pacbitun is offered. Initial settlement occurred in the Epicenter of the site during the Middle Preclassic period (900-300 b.c.) with a population rise through time until the final phase of the Late Classic period (A.D. 700-900), when density reached 550 persons (Periphery Zone) to 950 persons (Core Zone) per sq km. The impact on settlement size and distribution of topography, soils, water resources, and intensive agriculture (hillside terracing) is assessed and found to be significant. At the time of florescence, the population of the 9 sq km site is estimated to have been about 5000-6000 persons. This population estimate is compared with several coeval lowland Maya centers, and found to be reasonable for a medium-sized, Late Classic Maya center.