The archaeological evidence of social groups in Thailand has long been noted for not conforming to the standard paradigms of social organization. This paper investigates the concept of heterarchy before turning to consider current conceptions of the Bronze and Iron Ages in Thailand. New evidence from a recently excavated site, Ban Lum Khao, is considered and evaluated in the context of the existing knowledge of the period. The current understanding of the Iron Age is also evaluated and enhanced through the incorporation of data from two sites in northeast Thailand, Non Muang Kao and Noen U-Loke. The paper concludes that the data from prehistoric Thailand are better interpreted from a heterarchical perspective. The possible causative factors of stratiÆed social organization are considered from a heterarchical perspective, examining ceramic production, mortuary practice, demography, and environment.