The solvolysis of 2-phenylethyl-1-C14p-toluenesulphonate in absolute ethanol, glacial acetic acid, 90% formic acid, and anhydrous formic acid gave rise to products which showed rearrangements of the C14-labeled atoms from the C-1 to the C-2 positions to the extent of 0.3%, 5.5%, 40%, and 45%, respectively. The results constitute an unequivocal proof that phenyl participation occurs in the reactions studied. The different degrees of rearrangement found for the different solvent systems are in agreement with the concept that the solvolysis process may have a range of mechanisms between the two extremes of the nucleophilic or SN2 type and the limiting or SN1 type. In the solvolysis in absolute ethanol, a small amount of "unreacted" 2-phenylethylp-toluenesulphonate recovered from the reaction mixture was found to show isotope position rearrangement of almost the same degree as the ethanolysis product. This finding is tentatively attributed to the phenomenon of internal return involving an ethyl-phenoniump-toluenesulphonate ion-pair.