Hyperbranched and branched polymers were synthesized by one-pot reaction of the AB(2) monomer 4-(4'-chloromethylbenzyloxy)phenylacetonitrile (1). The polymerization of 1 was controlled by adding a chloromethylarene (A(1) comonomer) such as methoxybenzyl chloride and by adding TBAC (tetrabutylammonium chloride). Copolymerization of 1 with A(2) comonomers, bis(chloromethyl)arenes, gives the corresponding copolymers.