In the present paper, we develop a new biogeographic model for the biota of the Southwest Pacific, using 76 published phylogenies for a range of island endemics or near-endemic organisms. These phylogenies were converted to areagrams by substituting distributions for taxa. Paralogy-free subtrees (3-item statements) were derived from these areagrams and used as input data into LisBeth that uses compatibility analysis and an exhaustive branch and bound algorithm to produce optimal trees. A general areagram is derived from all three-item statements common to the optimal trees. The results of the analysis show that the Melanesian Rift is not a natural biogeographic area; the islands of the Southwest Pacific are more closely related to each other than they are to Australia; and New Caledonia has had a long history of biological isolation. There is support for a general period of mobilism during the mid-Cenozoic when the biota as a whole expanded its range in response to regional uplift. By comparing the general areagram with what is known about the tectonic development of the region, it is possible to both calibrate the nodes of the areagram, and to identify points of conflict between the geological and biological data.