A novel class of heterogeneous ethylene polymerization catalysts, derived from homogeneous metallacyclic zirconocene complexes is described. These complexes can be activated with methyl aluminoxane (MAO) and used for ethylene polymerization. The polymerization reaction begins homogeneously, but the homogeneous metallacycles self-immobilize during the polymerization process. Subsequent olefin polymerization is therefore heterogeneously catalyzed. This method of heterogeneous olefin polymerization is compared with a homogeneous and an alternate heterogeneous polymerization technique.