The two principal storage proteins of the cottonseed have been purified and partially characterized. They have apparent molecular weights of 52,000 and 48,000 and are both comprised of sets of isoelectric isomers. Both sets have nearly identical solubility properties, ultraviolet absorption spectra, and contain similar proportions of amino acid residues. Furthermore, both sets share antigenic determinants suggesting their origin from a common ancestral gene. However, only the 52,000 set appears to be glycosylated.