Rough fescue prairies were once common across the northern prairies but have now been almost entirely lost to a combination of agricultural expansion, energy development, fire suppression, and invasion by exotic species. Despite these pressures, remnant grasslands remain important in conserving biodiversity and as habitats for threatened species. In this project, we test the hypothesis that the density of Kentucky bluegrass (Poa pratensis), an invasive, exotic species, introduced across the Great Plains, is inversely relatedwith the density of plains rough fescue (Festuca hallii), the dominant native grass of northern fescue communities, and examine whether cattle grazing could help restore invaded prairies. We tested the relationship between the two species using 33 transects (0–44 m), located within patches of rough fescue prairie at the Batoche National Historic Site of Canada in Saskatchewan. Along each transect, we recorded the density of Kentucky bluegrass and plains rough fescue and used cattle exclosures to test the hypothesis that grazing reduces the abundance of the invader and increases the abundance of plains rough fescue. Although higher densities of Kentucky bluegrasswere negatively correlated with the density of plains rough fescue, grazing by cattle did not significantly reduce the density of Kentucky bluegrass, 6 yr after the initiation of grazing. However, cattle grazing also did not reduce the density of plains rough fescue, suggesting that it may provide a valuable tool to actively manage and restore invaded prairies. Our results also suggest that long-term monitoring and additional measurements of community diversity and productivity may be necessary to demonstrate the success of this restoration method.