Wool has been modified to render it more hydrophobic by two methods. The first method involved treating the wool with benzoyl, lauroyl, stearoyl, and dodecenyl chlorides and with trifluoroacetic anhydride. Substantial degrees of reaction with the wool were achieved when the correct solvent media and reaction conditions were used. These varied with the particular reagent employed. Pyridine was particularly effective with the acid chlorides, whereas dimethyl sulfoxide was best with trifluoroacetic anhydride. Pyridine is believed to function both as a swelling agent and as an acid acceptor in these treatments. The second method of treatment was the grafting of vinyl and allyl monomers to wool by the use of high energy radiation. Both 60Co γ-rays at 0.3 Mrad/hr. and Van de Graaff γ-radiation at 3 Mrad/min. were found to be highly effective. The presence of a swelling agent in the monomer solution was found to be essential even in the case of acrylonitrile in dimethyl formamide. Water and methanol in small amounts were found to be highly efficient swelling agents. Substantial quantities of monomer could be grafted in most cases without difficulty when the correct conditions were used.