The International Classification of Functioning, Disability and Health (ICF) (WHO, 2005) represents an international tool to address, plan, and evaluate complex psychosocial interventions. ICF represents a common metalanguage which aims to overcome conceptual profession-specific terminology and increase common understanding and coordination of complex health intervention processes. Even though strongly recommended by the WHO, UNICEF, World Bank, etc., its use is still limited due to the necessary transformations of specific constructs (e.g. in psychology) into the new meta-categories. The paper addresses attempts to transform traditional constructs in psychology and special education into the metalanguage of ICF and provides selected empirical evidence by means of performed usability studies in Austria and Germany of these transformation processes.