The growth of poly (N-vinylcarbazole) films during the electrochemical oxidation of N-vinylcarbazole at a Pt electrode in MeCN by repeated potential scans is controlled by the number of redox cycles and the choice of anion in the supporting electrolyte; for various anions studied (ClO4–, BF4–, PF6–, AsF6– and SbF6–) polymer film thickening is proportional to the number of cycles, and increases as the radius of the anion associated with the doped form of the polymer decreases.