The European linguistic diversity goes far beyond the official national languages of the present 27 member states of the European Union. In every country several languages of smaller or larger groups of speakers are used besides the official language or the languages of the majority population. These languages are autochthonous languages that have been used for a long time in the individual country as well as allochthonous languages of different groups of migrants and their descendants. The sometimes complicated relations between national, regional and minority languages within various countries are discussed in this volume. Besides reports on several countries, the general sociolinguistic and legal conditions are dealt with in overview contributions. In addition, the Dublin Declaration on the relationship between official languages and regional and minority languages in Europe is presented in 24 languages.