This is an Open access Book. Language promotion in German day-care centres is placed on an evidence-based foundation in this study: After a comprehensive review of sources from scientific literature as well as materials from public and civil society actors and the general public, it analyses which language support measures are used in Germany, who they are aimed at, how they are implemented and what information is available on their effectiveness. The result is a structured, systematic overview of the language support measures used in child day-care centres in Germany in the research period from 1949 to 2017.