Molecular events controlling cotton fiber cell wall elongation remain elusive. Although the carbohydrate composition of primary and secondary walls is well established, little is known about the structural and/or enzymatic proteins localized in fiber walls. If enzymatic hydrolysis and cross-linking of wall components regulates cell wall expansion, then identification of the protein components is essential. Ionically-bound wall proteins from 18 day post-anthesis (DPA) fibers were extracted with buffers containing NaCl, LiCl, and CaCl₂). The total amount of protein extractable from fiberwalls was constant until 20 DPA. Absolute amounts of several wall-associated proteins changed during fiber development from 15 to 50 DPA. Seven of the most abundant developmentally-regulated proteins have been electrophoretically purified. Amino acid composition analysis of these proteins will be compared to other known plant cell wall proteins. Analysis of cell wall hydrolyzates indicates that isodityrosine is present in cotton fiber cell walls.