This paper reviews the work on sociolinguistic aspects of the recent immigration of foreign workers and their families from Southern Europe and the Mediterranean countries of the Middle East and North Africa to West Germany. The continued presence of these foreigners presents almost laboratory conditions for the investigation of the initial and subsequent stages of contact-induced linguistic development in adults and children. The situation is particularly interesting here because many of the languages involved (Turkish, Arabic, Greek, Serbo-Croatian, Spanish, Italian and Portuguese) are typologically different from each other and from German.