A process for the polymerization of one or more addition polymerizable monomers to form a copolymer comprising multiple regions or segments of differentiated polymer composition or properties comprising contacting an addition polymerizable monomer or mixture of monomers under addition polymerization conditions with a composition comprising at least one olefin polymerization catalyst, a cocatalyst and a chain shuttling agent, said process being characterized by formation of at least some of the growing polymer chains under differentiated process conditions such that two or more blocks or segments formed within at least some of the resulting polymer are chemically or physically distinguishable.