Khok Charoen is a Neolithic habitation and cemetery site in the eastern Chao Phraya basin in Lopburi Province, central Thailand, dating to approximately 1000 BCE. It was excavated by the Thai-British Archaeological Expedition between 1966 and 1970. The demographic profile documents a high proportion of children, reflecting a rapidly expanding population according to the proposals of Jean-Pierre Bocquet-Appel. Caries and ante mortem tooth loss are common, suggesting a substantial agricultural component to the subsistence, notwithstanding the minimal evidence for agriculture in the ecofactual remains. Several lines of evidence point to a tall stature by the standards of recent Thais. Dental anatomical traits reflect the population’s expected “Sundadont” profile. The teeth are of moderately small size but with a shape more reminiscent of “Australoids” than other Neolithic to recent Southeast Asians. The mandibles display mixed affinities with a predominantly “Southern Mongoloid” anatomy combined with more Melanesian-like metrics. In summary, Khok Charoen can be interpreted as representing the transition between Mainland Southeast Asia’s pre-Neolithic Australoid foragers and its late Holocene, Southern Mongoloid farming inhabitants.