From the very beginning, research on language acquisition has been dom inated by single case studies in which children’s approx­ imations to one or more target languages (monolingual or multi­ lingual first language acquisition) or adults’ efforts to learn a foreign language (second language acquisition) are docum ented over a certain span of time. There are good reasons to continue this line of research, since it is difficult, for example, to find hom ogeneous groups of children or adults for comparative pur­ poses, especially in the realm of bilingualism. Bilingualism itself is so heterogeneous that comparisons across subjects, languages, countries, social classes etc., are difficult to make. O ur study may represent an exception since it involves a relatively hom ogeneous group of 19 children between age five and eight who are growing up with two first languages, German and Hispanoamericano. The children and their families live in or around Braunschweig, Germany. The children’s mothers were born and grew up either in South America, Mexico or Spain. Nearly all the families were established outside Germany. The fathers grew up in Germany with German as their first language. They later acquired Spanish as a second language in which most of them became fairly fluent. Many of the children regularly visit their m others’ country of origin during vacations. In Germany the children speak Spanish

with their m others but otherwise German. The families’ social background is upper m iddle class. They support and prom ote the bilingual developm ent of their children.