Styrene was copolymerized with ethylene using the geometry constrained Me2Si(Me4Cp)(N-tert-butyl)TiCl2 Dow catalyst activated with methylaluminoxane. Increasing the styrene/ethylene ratio in the reactor feed had the effects of reducing both the activity of the catalyst and the molecular weight of the copolymers produced. However, the higher the styrene/ethylene ratio used.. the greater the amount of styrene that became incorporated in the copolymer. We discuss these experimental findings within the framework of a computational analysis of ethylene/styrene copolymerization performed through hybrid density functional theory (B3LYP) In general. there was good agreement between the experimental and theoretical results. Our findings point to the suitability of combining experimental and theoretical data for clarifying, the copolymerization mechanisms that take place in alpha-olefin-organometallic systems. (C) 2004Wiley Periodicals, Inc.