The effect of 2,4,6-tri-I-butylphenol on the rate of polymerization of vinyl acetate and on the degree of polymerization of the resultant polymer has been determined. It is shown that the phenoxy radicals produced by hydrogen transfer do not reinitiate polymerization and that they disappear from solution by reaction with polyvinyl acetate radicals. The chain transfer constant is estimated to be 0.017 + 0.004 at 45" from molecular weight studies and 0.021 f 0.004 from rate studies. Stationary state concentrations of phenoxyl of the order of