The C163 Expert Committee of the European Rail Research Institute (ERRI) concerned with Railway Noise, has been developing theoretical models for the generation of wheel/rail rolling noise. These models have been brought together into a software package, called TWINS ("Track-Wheel Interaction Noise Software"). This is intended as a tool with which different designs of wheel and track can be assessed in terms of their noise generation. This paper begins by describing briefly the various theoretical models incorporated, the assumptions made within these models and their limitations. On the basis of the input and output parameters, a methodology is derived for the validation of the model by using full scale running tests. Two sets of experiments have been performed for a range of conditions in which the input parameters (the surface roughnesses of wheel and rail) were measured as fully as possible. As well as the sound pressure during train pass-by, a number of intermediate parameters were also monitored to allow validation of parts of the model.