This class deals with the typical and atypical development of more than one language in the broad sense, from birth or successively. Since bilinguals seldom use their languages in a balanced way, different dominance patterns arise and change over the lifespan, including the forgetting of the first language, referred to as language attrition - a phenomenon which is viewed as related to the acquisition of an L2. We will look at various developmental settings, different language phenomena and consider the impact of cross-linguistic differences on attrition and acquisition. By the end of the term students will be able to give an elaborate description of the phenomena of bilingualism in question and the factors of influence involved.