The Wathaman batholith, a major element of the Trans-Hudson orogenic belt in northern Saskatchewan and Manitoba, has an exposed strike length of 900 km. This immense body separates dominantly Archean (Rae-Hearne) provinces to the northwest from Early Proterozoic, arc-related terranes of the orogen to the southeast. Major- and trace-element data for 42 samples from the Saskatchewan part of the batholith are similar to those of Phanerozoic arc batboliths (for example, Sierra Nevada and Andean batholiths). Data plotted on trace-element discrimination diagrams show that the batholith has continental-arc affinities. U-Pb zircon geochronology of five main-phase granite samples suggests that most of the batholith formed between 1865 and 1850 Ma and is coeval with smaller plutons of the La Rouge arc. The main deformation of the batholith is limited by the 1830 Ma age of a late granite sheet that crosscuts folds and foliation of main-phase granites. The 15- to 25-m.y. crystallization span of the batholith is similar to the histories of many more recent continental magmatic arcs.