Raw data collected in screening assays should be appropriately analyzed to derive activity expressed as potency or efficacy values of tested compounds (IC50 or EC50 values). In this chapter the authors discuss standardized approaches to processing radioligand binding, enzyme and functional assays used in HTS and lead optimization. Detailed account is given in processing normalizing raw data and curve fitting. A glossary is also included defining the terms used for consistency in processing raw data in a standardized manner.