No research has been done to assess the occurrence of null and overt subjects in young bilinguals simultaneously acquiring a [+pro-drop] and a [-pro-drop] language. Previous research indicates that monolinguals set the pro-drop parameter at a very
early age. Failure to use null and overt subjects language appropriately in this population can be attributed to performance, rather than competence, factors. Research also indicates that bilingual language acquisition is neither significantly qualitatively nor quantitatively different from monolingual language acquisition. However, code-mixing is a phenomenon that characterizes bilingual acquisition. Syntactic code-mixing is extremely rare. Code-mixing does not stem from a lack of
language differentiation (the Unitary Language Hypothesis) but is instead attributable to factors such as language dominance, stage of development and sociolinguistic factors. As such, it is predicted that young bilinguals simultaneously acquiring a [+pro-drop] and a [-pro-drop] language will have similar levels of null and overt subjects to monolinguals acquiring each type of language. However, syntactic code-mixing may lead to a slightly higher incidence of null subjects in the [-pro-drop] language than in monolinguals acquiring this type of language. It is proposed that a
longitudinal study be carried out to test these predictions.