Computational chemistry is a valuable complement to experiments in the study of polymerization processes. This article reviews the contribution of computational chemistry to understanding the kinetics and mechanism of reversible addition fragmentation chain transfer (RAFT) polymerization. Current computational techniques are appraised, showing that barriers and enthalpies can now be calculated with kcal accuracy. The utility of computational data is then demons-sated by showing how the calculated l barriers and enthalpies enable appropriate kinetic models to be chosen for RAFT. Further insights are provided by a systematic analysis of structure-reactivity trends. The development of the first computer-designed RAFT agent illustrates the practical utility of these investigations.