This review summarizes recent results for ethylene/styrene copolymerization using half-titanocenes containing anionic donor ligands, Cp'TiX2(Y) (X = halogen, alkyl; Y = aryloxo, ketimide etc.)-cocatalyst systems. The product composition, the styrene incorporation and microstructures in the resultant copolymers are highly influenced by the anionic donor employed. A methodology for an exclusive synthesis of the copolymers even under high temperature and high styrene concentrations has been introduced on the basis of a proposed catalytically-active species in this catalysis.