In Chapter 3 we introduced two hypotheses about the acquisition process in young bilingual children exposed to two languages from birth in a separate fashion: the separate development hypothesis, which proposes that a bilingual child's morphosyntactic development proceeds along separate, non-intersecting lines for each language, and the transfer theory, which proposes that morphosyntactic development in the one language is carried over into the other. When in Chapter 3 we discussed the possible empirical bases on which to approach either hypothesis, it was pointed out that for each of the languages that the child was exposed to we would need a corpus of child utterances consisting of lexical items from one language only. In the present study investigating the speech production of a young Dutch-English bilingual girl, Kate, two such sets of data were present: we collected a substantial number of utterances containing both only Dutch and only English lexical items. Thus, we were able to address the question whether and to what extent Kate's two languages were developing separately as far as morphosyntactic features go.

In the analyses of Kate's use of morphology and syntax (cf. Chapters 6, 7 and 8) we were trying to find positive evidence for the separate development hypothesis.