Genetic variability in upland cotton germplasm appears to be limited for many traits. Segregation for several AFIS fiber quality traits and yield-related components was followed in six cotton populations (adapted × adapted) through the F₂ and F₃ generations. Heritability estimates were obtained using segregating and nonsegregating populations as estimates of phenotypic and environmental variation (F₂ generation) and regression methods (F₃ generation). For some traits variation among parent plants exceeded that of the F₂ generation. Yield-related traits (lint percentage and lint wt/seed) were moderately to highly heritable in most of the populations and generations, while fiber quality traits, such as fiber length and short fiber content were more population- and/or environment dependent. Short fiber content appears to be heritable when measured in the F₃ generation, but not on single F₂ plants, while the situation was just the opposite for lint weight seed^-1. As expected, heritability estimates for traits related to trash content were largely not heritable.