The reconstruction of Laurentia, Australia, and Antarctica into a Proterozoic supercontinent is evaluated by analyzing the fit of Precambrian provinces defined by isotopic and geochronologic mapping. The analysis is complicated by allochthonous segments of the Antarctic and eastern Australian margins. Removal of the allochthonous provinces produces a closer fit of the continents; there is a match of Early Proterozoic basement between southwestern Laurentia and the only exposure of craton known from the paleo-Pacific margin of Antarctica. In addition, western Laurentia is brought closer to the Australian Gawler block, consistent with provenance interpretations of the Belt Supergroup. Removal of the allochthonous provinces by right-lateral translation relative to the Antarctic craton margin places them in a pre-750 Ma position where they could be southwestward extensions of the Yavapai-Mazatzal and Grenville provinces of southern Laurentia. This modified reconstruction leads to a prediction of extensive Archean basement in Antarctica between the South Pole and Victoria Land, a prediction partly borne out by Archean rocks in the Miller Range of the Transantarctic Mountains; it also predicts the presence of 1.4Ga rapakivi granites in the Transantarctic Mountains basement. This configuration implies assembly of the Australia-Antarctica Gondwana margin by terrane accretion following, or accompanied by, left-lateral translation. This is compatible with a tectonic regime of clockwise rotation of Laurentia relative to Australia and Antarctica after rifting. Thus, the proposed supercontinent, with some modifications, has potential for explaining several aspects of the pattern of Precambrian provinces in the three continents.