Nitrogen (N) is often the nutrient applied in greatest quantity to cotton (Gossypium hirsutum) and the nutrient most subject to transformation in the environment. While a standard N recommendation for cotton has been 110 kg. N per Mg lint, we hypothesized that small-seeded, contemporary cotton cultivars might require less N than did those previously grown. A common experiment was done in AR, AZ, KS, MS, NC, OK, SC, TN, TX(2) for two years to determine the response of modern cotton cultivars to N rates, to evaluate the utility of pre-plant soil nitrate testing in arid and humid regions, and to assess the effect of N rates on cultivars with different sized seed. Treatments were cultivars with planting seed of different weight ranges, and four N rates, 0, 45, 90, and 134 kg/ha. Only half of the sites responded to applied N. High levels of soil nitrate (> 91 N-NO₃ kg/ha) were found a two western sites, and 45-73 kg N-NO₃/ha. was found at locations in the Mid-South. N increased plant height and number of fruiting nodes, decreased crop maturity, and increased seed weight and lint yields up to a maximum rate of 84-121 kg. total available N/ha. Considering only sites that responded to N, maximum lint yields were achieved with 90 kg total available N/ Mg lint produced. Cultivars with large and medium seed had higher yields in response N that did small-seeded cultivars. Large seed size increased fiber length, strength, fiber length uniformity and decreased micronaire. No significant interactions of seed size and N rate were found.