As archeological research in mainland Southeast Asia progresses beyond the pioneering stage, the emerging data pose a number of challenges to theories of socio-political development. Attempts to apply models assuming nested, conical, hierarchical progressions derivative from the band-tribe-chiefdom-state continuum often seem inadequate and somehow unable to account for the significant socio-political dynamics that are increasingly evident from the data. This chapter proposes that a shift in modeling the region's socio-political trajectory away from a stepprogression, hierarchical approach toward a dynamic, heterarchical approach will advance understanding of this region's distinctive social development and will contribute to broadening and refining theory on the formation of states and the development of social complexity.