There can be considerable variation in the fiber quality produced by a particular cotton (Gossypium hirsutum L.) genotype, depending upon the variation in environments under which the genotype is grown. The purpose of this series of experiments was to clarify the role of the amount of sunlight in determining various fiber quality traits. Altering the canopy light environment by a variety of techniques in 1991 and 1992 showed that lint yield increased or decreased as the canopy light level increased or decreased. Changes in the number of bolls per unit ground area was the yield component responsible for these lint yield differences. Light enhancement did not consistently improve fiber quality. However, a 30% shade treatment reduced both fiber strength and micronaire (MIC) by 6%. Periods of fiber development that were sensitive to low light conditions were not conclusively established by altering the timing and duration of exposure to shaded conditions in 1993 and 1994. However, the fiber data trends in 1993 tended to indicate that fiber strength developed from 0 to 21 days post anthesis (DPA) and MIC developed after 21 DPA. Both the yield and quality of lint produced would benefit from techniques that either increase the amount of sunlight intercepted by a canopy or that utilize the intercepted sunlight more efficiently.