This chapter describes the approaches to evaluate a read­across prediction and document it sufficient for regulatory acceptance e.g. for REACH. It defines the criteria that must be addressed in order to assess the confidence of such a prediction. These are the robustness of the category and the strength of the evidence associated with read­across. There is no rigid framework to evaluate and apply confidence to a prediction, but evidence must be provided to assure regulatory acceptance. The documentation to support such a prediction is described, as are the available training, guidance and education needs in this area.