The main objective of this paper is to show that young children infer
grammars for the primary data on the basis of innate knowledge (univer
sal grammar). The most interesting cases are intermediate grammars, wh
ich allow sentence structures that do not correspond to the experiment
al data (but to some other natural language) and disallow sentence str
uctures that are grammatical with respect to the target grammar. The i
nvestigation concentrates on the setting of three parameters that are
held to describe adult German, a V2 language: the Case parameter, the
head-position parameter, and the finiteness parameter. It will be show
n that bilingual as well as monolingual children may abduce ''wrong''
grammars, which, however, correspond to other V2 languages, like Yiddi
sh, for example. One of the possible reasons for wrong choices within
a parameterized grammatical system will be discussed, namely the confu
sing categorical status of complementizers.