Annually planted winter wheat is the major cool-season livestock forage enterprise in a large part of the southern Great Plains and is a good complement to warm-season perennials. However, gaps in both fall and spring exist in the system. Cool-season perennial grasses that have origins in the Northern Plains or western regions of the United States may help fill the gaps, but only recently have attempts been made to introduce them to the southern Great Plains. The objectives of these studies were to evaluate the potential of several cool-season grass species for forage production and quality through the fall and spring seasons. The studies were conducted at the Grazinglands Research Laboratory near El Reno, OK over a period of 4 years on Brewer silty clay (Fine, mixed thermic, Pachic Argiustolls). Growth rate and quality of nine different entries of cool-season perennial grasses were evaluated. Three replicates of each entry were planted in 27 x 46 m plots with ~ 2-m borders. Fertilizer was incorporated at the rate of 56 kg N ha^-1 before planting and each August during the experiment. They also received a spring application of 84 kg N ha^-1 in February each year. Four ¼ m² quadrats were selected at random from each plot and clipped to 4 cm stubble height at 28-d intervals from March through June, 1995. In the subsequent three years, four (1995-96) or two (1996-97; 1997-98) quadrats per plot were clipped at 28-d intervals starting in October for the fall season and in February for the spring season. The clipped herbage was weighed, dried at 60^oC in a forced draft oven, reweighed, and ground to pass either a 1-mm (1995, 1996) or 2-mm (1997, 1998) screen in a Wiley mill. Ground subsamples were stored in plastic until analyzed for DM, ash, N, neutral detergent fiber (NDF), acid-detergent fiber (ADF) and in vitro organic matter disappearance (IVOMD) using near-infrared reflectance spectroscopy calibrated with a subset of the total samples. Each year the plots were mowed as hay in July after the final harvest and staged in late August with a rotary mower. Yield (DM) and quality data were analyzed using the MIXED procedure in SAS as a split plot in time with year and harvest date being repeated variables. Block was the random variable. In addition, days of growth were calculated using October 1 and January 1 each year as the initial date for fall and spring growth. Yield of DM, percentage and yield of crude protein and digestible dry matter were regressed on days to determine daily changes. Growth rates and changes in quality will be discussed along with the application to grazing systems in the southern Great Plains.