A supported catalyst composition and process for preparing high molecular
weight polymers of one or more addition polymerizable monomers,
especially propylene, said composition comprising: 1) a substrate
comprising the reaction product of a solid, particulated, high surface
area, metal oxide, metalloid oxide, or a mixture thereof and an
organoaluminum compound, 2) a Group 4 metal complex of a polyvalent,
Lewis base ligand; and optionally, 3) an activating cocatalyst for the
metal complex.