Stepwise discriminant function analysis and Mahalanobis's generalized distance are applied to 36 measurements recorded in crania from Australasia and Oceania for assessing biological relationships and possible origins of these populations. Craniofacial variation in Australia is found to be clinal. There is extreme diversity in the Murray River Valley and southern Queensland cranial series. Multiple origins of the Australians are not supported by these results. Although selection and other processes cannot be completely ruled out, gene flow and restrictions to the exchange of genes can explain most of the morphological patterning observed. Breadth and length dimensions of the vault, interorbital breadth, biorbital breadth, palate length, and upper facial height are among the most important discriminators. Viewed within the broader context of Asia and the Pacific, Australians represent a biologically distinct population, one sharing ancestral ties with Melanesians but not with the recent populations of Asia and the rest of the Pacific. The latter represent a second major population complex.