The Belize River Archaeological Settlement Survey (BRASS) has completed the first phase of fieldwork (1983--1989) involving regional survey and preliminary test excavations in Belize. This work was aimed at gaining a general understanding of prehistoric settlement patterns and chronology in the upper Belize River area of the central Maya lowlands. The results of this phase of the project have demonstrated the complexity inherent in ancient Maya adaptation to the lowland environment. Settlement was far from homogeneous and restricted to the Belize Valley; it occurred in varying densities in all major zones, including the valley, foothills, and interior mountainous uplands.