Eight cultivars were evaluated for their yield and fiber characteristics over a three year period, and 13 cultivars were tested for two years, at four locations in Spain. Significant differences were obtained among cultivars (genotypes), locations (environments), and years. The variance was higher for location, year, and the location*year interaction than the other components. The genotype*environment interaction was significant only when Acala SJ- and the Ecija location were included in the analysis. Otherwise, the genotype*environment interaction was not significant for yield, earliness, fiber length, strength or micronaire. Significant differences exist among cultivars for seedcotton yield, earliness, and fiber characteristics, but less variability for yield was expressed compared to fiber characteristics. Variability among cultivars in first harvest was much higher than total seedcotton yield. Fiber characteristics had greater stability over environments compared to yield. Tabladilla 16 was the most productive and earliest of the cultivars tested. Since the genotype*environment was not significant in these studies, it is possible to select and identify cultivars with high adaptability for the environments in the Guadalquivir Valley in Spain.