This book investigates second language acquisition and in particular the spontaneous acquisition of Italian as an interlanguage -to solve communicative problems-by Spanish speaking immigrants in German Switzerland. Although the Swiss immigration policy requires linguistic and cultural integration, intercultural contact is rare and integration via acquisition of local languages is difficult given the diglossic situation (Hochdeutsch and Swiss for written and oral communication). Therefore Spanish speakers naturally turn to Italian, given the structural proximity of both languages.