The practical use of such nuclear model codes requires a considerable numerical input that describes the properties of the nuclei and the interactions involved. Experts have used a variety of different methods and input data sets, often developed over many years in their own laboratories. Many of these input databases are poorly or not at all documented, and are not always available for other users. With the trend towards reduced funding for nuclear data evaluations, there is a real threat that the immense amount of accumulated knowledge of nuclear data input parameters and associated calculations may be compromised or even lost for future applications. Therefore, the IAEA has undertaken an extensive coordinated effort to develop a library of evaluated and tested nuclear-model input parameters: RIPL-2.--Publisher's description.