Abstract: Silicon-bridged transition metal compounds and their use as alpha-olefin polymerization catalysts are disclosed. The polymerization catalyst comprises a chiral silicon-bridged metallocene of the following structure: ##STR1## where M is a transition metal, X' and X" are the same or different hydride, halogen, hydrocarbyl or halohydrocarbyl groups having up to about 6 carbon atoms, A' and A" are each the same or different asymmetrical mononuclear or polynuclear hydrocarbyl or silahydrocarbyl moieties and S' is a bridge of 1-4 atoms selected from the group consisting of silanylene, silaalkylene, oxasilanylene, and oxasilaalkylene, and may include an alumoxane. Specifically, the transition metals are titanium, zirconium, and hafnium.