Regional settlement patterns from the Formative through Post-Classic Tiwanaku periods (1500 B.C.-A.C. 1100) in the Tiwanaku Valley of Bolivia are explored. Ecological considerations, rank-size interpretations, and some aspects of central place theory are incorporated into this investigation of the evolution of regional social and political organization of the Tiwanaku polity. Taken together, the analyses point away from reconstructions of the Tiwanaku polity as a highly centralized and monolithic state organized in a ''pyramidal'' fashion. Settlement patterns indicate the presence of sub-system settlement enclaves with differing relationships to the capital. The identification of sub-system settlement units lends support to suggestions arising from recent study that, by the Post-Classic Period, Tiwanaku society was segmentary in nature and organized into a nested hierarchy. These findings are consistent with ethnohistorically-derived constructs of indigenous Andean sociopolitical structure.