Phytohormones play a critical role in regulating the development of cotton fibers. As early as 1973, Beasly and Ting showed that auxin and gibberellic acid (GA) are required for fiber development in cultured ovules. In our laboratory, we have confirmed that GA is necessary for the development of fiber in both fertilized and unfertilized ovules and have now taken the initiative to characterize key genes involved in GA signaling in cotton. Based on literature, genes involved in the GA signaling pathway have been identified using GA response mutants. One class of GA-insensitive dwarf mutant includes gid1 from rice that was shown to encode the GA soluble receptor (Tanaka et al., 2005). Moreover, GID1 bound to SLR1, a rice DELLA protein that represses the GA signal, in a GA-dependent manner in yeast cells. To evaluate the role of cotton gid1 and slr1 orthologs (Ghgid, Ghslr) in fiber development, these genes were cloned and characterized. Using yeast-two hybrid analysis we have investigated if the cotton genes interacted similar to those of rice. Additionally, we tested if GID1 interacted with the GhSLR and similarly if GhGID interacted with SLR1. The development of transgenic cotton over-expressing these genes both in a fiber-specific manner and constitutively is underway. The altered GA response in these plants along with these preliminary results will give us insight to the role and regulation of the GA response pathway in relation to fiber development and enable us to identify genes responsible for the genetic diversity of fiber yield and quality traits.