The background and summary of the events that led to the discovery and confirmation of an unusual and unexpected mode of polymerization of certain vinyl monomers is presented. Originally, the process was described as an alternating intra-intermolecular chain propagation mechanism. For convenience and because cyclic structures are introduced into the polymer chain, the term cyclo-polymerization has been adopted. Early attempts to determine the relationship of cyclopolymerization to stereochemical control and to ladder polymer formation are reviewed. Also, it is pointed out that within 10 years of the introduction of the cyclopolymerization concept, worldwide commercialization of certain cyclopolymers and cyclocopolymers had begun. The extent of the research activity in this area of chemistry and its relationship to commercialization are emphasized. Two areas of research activity that are featured are chirality induction into well-known polymers and synthesis of conjugated polymers via cyclopolymerization. Both areas are discussed, and suitable examples are included.