Technical Abstract: Genotype × environment interactions and trait correlations significantly impact efforts to develop high yield, high quality, and environmentally stable Upland cotton (Gossypium hirsutum L.) cultivars. Knowledge of both can and should be used to design optimal breeding programs and effective selection criteria. In this study, we examined the genotype × environment interactions and trait correlations present in the 70-year Pee Dee cotton germplasm enhancement program. Since beginning in 1935, the Pee Dee program has employed a variety of unique germplasm and breeding methods to release greater than 80 improved germplasm lines and cultivars. Results suggest that significant genotype × environment interactions exist for several agronomic and fiber quality performance traits that are mostly due to changes in magnitude. Negative genotypic correlations still persist between lint percent/lint yield and fiber length/fiber strength. However, apparently the breeding methods and selection criteria used over 70 years have lessened the negative relationship between agronomic performance and fiber quality over time to some degree. The results provide cotton breeders a resource to select specific Pee Dee germplasm lines for increased environmental stability. Cotton breeders can also use the information herein to select specific Pee Dee germplasm lines that represent rare recombination events that combine high yield and fiber quality potential.