The property of rubber elasticity is displayed by an ever increasing range of polymers-hydrocarbon, polar and even inorganic. Such rubbery polymers, however, differ in the way by which they are made, in their chemical and physical properties, in the way in which they form network structures and in the way in which they age. Such differences are due, primarily, to differences in their underlying chemistry and chemical structure. It is the aim of this monograph to survey, in a single volume, the chemistry of these rubbery polymeric materials and to cover such aspects as their preparative chemistry, relationship of chemical structure to properties, the molecular nature of high elasticity, cross linking and other chemical modification and ageing. This has been done, not simply because rubbery materials are so fascinating in their own right but also because of their industrial importance. It is therefore hoped that this book will help both the polymerization chemist and the rubber technologist to have a better and broader based understanding of the materials with which they are concerned and to be able to suggest directions along which developments may proceed.