Late season changes in lint weight were measured between September 29 and October 13, 1989 in plots subjected to three irrigation treatments which had different levels of crop boll maturity. The irrigation treatments represented low water stress (LWS), moderate water stress (MWS), and high water stress (HWS). Temperatures during the two-week period resulted in an accumulation of 77 DD60s which were slightly above the 20-year average of 70 DD60s. Lint weight increases of 35, 22, and 31 g per 100 bolls occurred during the two week period in treatments LWS, MWS, and HWS, respectively. Estimated yield increases for the same period calculated from boll tagging data and a crop maturity model were 516, 476, and 352 kg lint per ha for treatments LWS, MWS, and HWS, respectively. Estimated lint yield changes were strongly related to level of crop maturity on September 29, which was 50, 61, and 77 percent for LWS, MWS, and HWS, respectively. The most consistent change in fiber properties was improvements in strength and uniformity of immature bolls from all treatments. The amount of leaf area or differences in canopy senescence did not limit late season weight increases of immature bolls.