Experiments were conducted in 1987 to evaluate the response of cotton grown on two soil types of the Texas Southern High Plains to nitrogen and phosphorus application rate and timing under varying water supplies. Nutrients were applied preplant and at square initiation on dryland, limited irrigation, and fully irrigated plots. Sidedress application of nitrogen increased lint yield above the preplant treatment and split applications produced the highest yields. Preplant phosphorus increased yield only under dryland conditions while sidedress applications increased yield under all water supplies. A ratio of 5:1:0.5 for water, nitrogen, and phosphorus should be maintained to maximize utilization of the limited water resource on the Texas Southern High Plains.