Cotton yields in the U.S.A are well below the potential. The five-year average yield for cotton in Arkansas is 886 lb lint/acre, whereas the theoretical maximum lint yield of cotton is 3720 lb lint/acre. Of even greater concern to the producers and the cotton industry is the extreme variability in cotton yields from year to year. Yield is controlled by genetic and environmental factors as well as by cultural inputs. Of these, it is thought that environmental factors exert the major influence on yield development during the season. Researchers have suggested that changes in cotton germplasm over the past thirty years may have resulted in reduced tolerance of modern cultivars to environmental stress. However, the nature of the susceptibility and growth response of cotton to environmental stress is not well understood. Past experience and recent research has indicated that high temperature is the major factor adversely affecting cotton yields during the season with a strong correlation existing between high temperatures and low cotton yields. This has been related to effects on the reproductive development of the crop. But the specific nature and timing of these effects is not well understood. Research is needed to characterize the effects of high temperature on reproductive development. An overall goal of this study is to formulate theoretical strategies to counteract early and mid-season high temperature stress to insure yield stabilization including new plant growth regulators, precise irrigation timing, foliar sprays to improve pollination and seed set efficiency in cotton crop, and improved genotypic temperature tolerance during the reproductive stage in cotton varieties.