This volume focuses on the learning of host-country languages by migrants in Europe. It identifies, clarifies, and offers insights into issues and central questions related to the learning of host-country languages with an emphasis on adolescent and adult language learners in formal and informal settings. The book draws on data collected following the refugee 'crisis' in Europe of 2015-16, which led to dramatic increases in the number of migrants arriving in Europe. [Individual chapters are indexed in ERIC.]