A catalyst composition for the polymerization of propylene is provided. The catalyst composition includes one or more Ziegler-Natta procatalyst compositions having one or more transition metal compounds and an internal electron donor, one or more aluminum containing cocatalysts, and a selectivity control agent (SCA). The SCA is a mixture of an activity limiting agent (ALA) and selectivity determining agent (SDA) such as a non-silane composition. The present catalyst composition is silane-free, has high catalyst activity and high stereoselectivity, and is self-extinguishing.