This chapter shows that controversy versus praise alongside the change in perspective about disability and development that the international classification of functioning, disability and health for children and youth (ICF-CY) model triggered in policy and practice in various countries. It combines in one international compendium, examples of good practice in using the ICF/ICF-CY and examples of criticisms, highlighting areas for further development. Our contributors used the ICF or the ICF-CY term depending on the version that was used in their studies and depending on what they believe is the best classification system for young people. The chapter argues the debate around the usefulness of the ICF/ICF-CY in the context of special education needs provision in England, which has not happened so far, at least not at the policy level. World health organization (WHO) has issued a communication that the versions of the classification should merge forming one single ICF manual.