Little is known about wetland selection by Lesser Scaup (Aythya affinis) during any phase of the breeding cycle, particularly in the northern boreal forest region, where most of the North American population of scaup breeds. We used survey data (1989-98) for 402 wetlands near Yellowknife, Northwest Territories, Canada to assess frequency of scaup brood occurrence. In 1999, features of 80 randomly selected wetlands (21 used and 59 not used by scaup broods) and 27 wetlands used repeatedly by brood-rearing scaup were evaluated (N = 107 total). Discriminant function analysis using all wetland measurements was used to classify scaup use of 77 randomly selected wetlands; classification criteria were subsequently used to predict brood use of the remaining 30 hold-out wetlands. This randomization procedure was repeated 100 times, producing an average classification success of 88% (95% CI = 77% to 97%). Broods occurred more often on larger, deeper wetlands with water lilies and amphipod crustaceans, the latter being an important food for adults and ducklings. Wetlands created during road construction were used less often, possibly because these tended to be smaller, shallow, less likely to have amphipods, and had a different vegetation regime than natural wetlands.