Enhancement of the rates of cationic polymerizations initiated by onium salts has been achieved through the use of oligomeric and polymeric electron-transfer photosensitizers derived from a polymerizable compound substituted with a polynuclear aromatic group, including epoxides, oxetanes, and ethylenically unsaturated compounds. The polymerizable compound is substituted with residues derived from anthracene, naphthalene, perylene, pyrene, fluorene, carbazole, indole, benzocarbazole, acridone, phenothiazine, and thianthrene, particularly carbazole.