In the southern Great Plains of USA, the most important winter forage crop is dual-use (forage and grain) wheat (Triticum aestivum L.). Unpredictable autumn rains often delay planting of wheat, resulting in a lack of forage for cattle to graze into the winter and early spring. Introduced cool-season perennial grasses may complement or replace forage from dual-use wheat and dormant perennial warm-season grass pastures. Traditionally recommended cool-season perennial grasses (referred to as continental or summer-active types) for the southern Great Plains, i.e., wheatgrasses, are limited in their potential to complement dual-use wheat because of low early-season productivity and poor persistence during severe and prolonged summer drought. Consequently, improved cool-season perennial grasslands require frequent reestablishment in environments considered marginal for their existence, increasing costs of forage production. A new type of cool-season perennial grasses with summer dormancy trait, originating from the Mediterranean Basin, has been proven well adapted to the environments of the southern Great Plains. The research on adaptation of these grasses and mechanisms of summer dormancy has been conducted at Texas AgriLife Research and Extension Center in Vernon, TX since 2000. In 2005, we initiated a forage improvement program based on accessions of summer-dormant orchardgrass (Dactylis glomerata L.) and tall fescue [Lolium arundinaceum (Schreb.) Darbysh.], and Mediterranean-origin accessions of perennial ryegrass (Lolium perenne L.). Using traditional breeding approaches, we selected several lines with superior forage characteristics and persistence when compared to commercial cultivars (summer-active and summer-dormant types). New cultivars of summer-dormant cool-season grasses originating from this breeding program are expected to be released in the near future. These new forage grasses will be better adapted to changing climatic conditions of the southern Great Plains than traditional cool-season perennial grasses and help sustain economic viability of this region.