In order to further develop the applications of polymers, it is necessary to control their useful life, i.e., we must know how to stabilise polymers effectively. We must therefore understand the mechanisms that cause polymers to degrade and the effects of processing and modifying the polymers on their stability. The 1st Conference on Polymer Modification, Degradation and Stabilisation (MoDeSt 2000) was held in Palermo, Italy in 2000. It brought together scientists and technologists from a range of academic and industrial backgrounds to discuss the topics in a dedicated environment. This volume of Macromolecular Symposia presents invited lectures from two of the sessions -- 'Processing and Melt Stabilisation' and 'Functionalisation and Reactive Processing'. It therefore represents a good sample of very recent work in these areas.