The cationic polymerization of indene initiated with cumyl chloride and stannic chloride in solution in methylene chloride at -15 degrees C is controlled up to M-n = 20 000, with a low transfer to monomer constant (k(trM)/k(p) = 9 x 10(-4)). Experiments carried out in compensated media allowed kinetic measurements and showed that the sharp decrease of the M-n at high indene concentrations results from zero order transfer due to the change of dielectric constant (k(tr)/k(p) = 1.5 x 10(-3) for a dielectric constant of 5.4). In methylene chloride, for indene concentrations higher than 2 mol.L-1, the heat release of the fast reaction adds up to the zero order transfer to lower the molar masses. Bimodal distributions result from propagation on free ions and ion pairs.