Thus far in our program of applying a triangulation method to the “rediscovery” of Ancestral Polynesia within the framework of a phylogenetic model we have dealt with domains all having a material basis: the environment, subsistence, cuisine, and technology. We now move, however, largely out of this materialist realm, as we attempt to interpret fundamental social structures by which the Ancestral Polynesians organized themselves, as well as the belief systems – the mentalités – that regulated their daily lives. Archaeology will have only minimal input to these investigations, even though its contribution could potentially be much greater. To return to our surveying analogy, we are now restricted to fixing, by triangulation, the domain of interest from only two independent “lines of sight.” We must consequently depend more heavily on linguistic evidence for cultural (emic) categories, and will need to be as rigorous as possible in constructing semantic history hypotheses, informed by intensive ethnographic comparison. Such rugged terrain is not for the faint-hearted among culture historians. Yet we do not hesitate, for the landscape now within the scope of our surveying instruments – hazy though its topography may be – reveals the essential contours of ancient Polynesian societies.