The main goal of this project is to investigate the consequences of bilingualism for children's linguistic and cognitive development. In contrast to widespread intuitions about the disadvantages of bilingualism, cognitive studies reveal enhanced executive functions for bilinguals. A specific objective of the study comprises establishing relationships between the level of bilingualism and cognitive growth by adressing the question of how bilingual a child needs to be to develop enhanced executive funcions. The project will be executed in close cooperation with a parallel project in Utrecht/Amsterdam amongn bilingual children speaking immigrant languages.