Quasiliving polymerization of indene, i.e., an increase of the molecular weight of polyindenes with the cumulative amount of consumed monomer, has been demonstrated using the “H2O”/ BCl3, 2-chloroindene/BCl, “H2O”/TiCl4, 2-chloroindene/TiCl4, and cumyl chloride/TiCl4initiating systems in CH2Cl2solvent at -50°C. However, chain transfer operates in every system investigated, and sets a limit toDPn,max. The efficiency of the 2-chloroindene and cumyl chloride initiators is very low. The behavior of BCl3and TiCl4coinitiators on the polymerization has also been investigated.