Today's growing mobility in European urban regions results in a more widespread language diversity, which is increasingly challenging current language policies. Against this background, this volume deals with the interface between language policy, language planning and actual practices. The impact that prevailing language policies have on language practices is observed in a series of urban settings, leading to a reflection on the changes that need to be brought about to promote social inclusion and valorise linguistic diversity in a context of globalisation-affected and migration-related multilingualism. The topics of discussion draw on different theoretical perspectives and span the research fields of linguistics, education, (family) language policy and planning, language acquisition and sociology.