A compilation has been made of 523 analyses of Sm-Nd isotope ratios of intrusive and extrusive rocks, and presumed orthogneisses, within the western Churchill Province. The data indicate that the region is dominated by juvenile crust extracted from the upper mantle at 2.7-2.8 Ga, emplaced over older crustal domains with extraction ages clustering at 2.9-3.1 Ga, 3.3 Ga, and possibly 3.5-3.6 Ga. Despite extensive Proterozoic igneous activity within the region, there is very little evidence for emplacement of juvenile magmas younger than 2.6 Ga.