Abstract: The Dow Chemical Company is world’s largest practitioner of homogenous catalysis including production of polyolefins. Olefin polymerization with homogeneous catalysts allows for unprecedented control over polymer composition and microstructure. This talk will discuss the development of various molecular catalysts for the production of ethylene-based copolymers such as ethylene-styrene and ethylene-1-octene. Particular emphasis will be giving to the most recent research aimed at modifying catalyst reactivity toward alpha-olefins. Rational ligand modifications of molecular catalysts allowed us to dramatically alter their reactivity from being very good to being very poor alpha-olefin incorporators during ethylene/alpha-olefin copolymerization reactions.