Polymerization of Heterocycles (Ring Opening) is a collection of papers presented at the International Symposium on Polymerization of Heterocycles (Ring-Opening) held in Warsaw, Poland on June 23-25, 1975. The first paper describes the developments and physical meaning of ion pairs and higher ionic aggregates. Another paper explains the process of obtaining linear polymers, containing rings in the main chain. The book interprets the various behaviors of polymers that can result in high optical yields of stereoelectivity ratios equal to 8. The text then discusses future trends in aldehyde and carbonyl polymerization, including some problem areas pertaining to failures to homopolymerize or copolymerize tetrachloroethylene oxide. Another paper reviews the elemental reactions of selected combinations of copolymerization; the next paper discuses aspects of the mechanism of nucleophilic opening of epoxide rings through studies of certain kinetics. The book then analyzes the ability of lactams to undergo ring-opening polymerization, which mainly depends on the ring size and on the substitution and presence of heteroatoms in the lactam ring itself. The text also discusses the preparation, properties, and applications of the heterochain polymers in medicine or biologically active materials. The book can provide useful information for biochemists, researchers dealing with inorganic and organic compounds, and scientists working in the fields of chemistry such as synthetic chemistry, as well as polymer engineering.