Water availability is a major factor influencing cotton cultivar performance and sustainable cotton (Gossypium hirsutum L.) production in the southeast USA. An increased understanding of the response of diverse cotton germplasm lines to supplemental irrigation could aid in future efforts to develop cultivars targeted to irrigated or dryland environments. In this study, thirteen germplasm lines were selected from the Pee Dee (PD) germplasm collection and evaluated to measure the effect of supplemental irrigation on a number of agronomic and fiber quality traits important to cotton production systems. This study shows the importance of comparing individual genotype response to supplemental irrigation for agronomic and fiber quality traits to efficiently target genotypes for irrigated or dryland environments.