Technical Abstract: Seeding perennial cool-season grasses may be used to extend grazing seasons on rangeland. Few available cultivars have been evaluated for livestock performance. Twice replicated 3-ha pastures were seeded to 'Rosana' western wheatgrass (WG) (Pascopyrum smithii), 'Luna' pubescent WG (Elytrigia intermedia), and 'Hycrest' crested WG (Agropyron spp.) in fall 1994. Yearling steers (n=8) were grazed from 9 May to 12 June 1997 and 24 Apr. to 15 June 1998. Standing crop (SC) was 912, 448, and 608 kg/ha for Hycrest, Luna, and Rosana in May 1997 and 553, 330, and 469 kg/ha June. SC was 1,223, 680, and 750 kg/ha for Hycrest, Luna, and Rosana in Apr. 1998 and 1,643, 1,032, and 889 kg/ha in June. Gains were 1.2 kg/head/d in 1997 and did not differ among varieties. Gains were 1.4, 1.3, and 1.1 kg/head/d for Hycrest, Luna, and Rosana from 24 April to 20 May 1998, and gains on Hycrest were greater than on Rosana. Gains from 20 May to 15 June and 24 Apr. to 15 June did not differ among species. With these conditions and standing crops steer gains generally similar among species in the Northern Great Plains.