Linguistic Interdependence and the Educational Development of Bilingual Children

The central thesis of this paper is that a cognitively and academically beneficial form of bilingualism can be achieved only on the basis of adequately developed first language (L1) skills. Two hypotheses are formulated and combined to arrive at this position. The "developmental interdependence" hypothesis proposes that the development of competence in a second language (L2) is partially a function of the type of competence already developed in L1 at the time when intensive exposure to L2 begins. The "threshold" hypothesis proposes that there may be threshold levels of linguistic competence which a bilingual child must attain both in order to avoid cognitive disadvantages and allow the potentially beneficial aspects of bilingualism to influence his cognitive and academic functioning. These hypotheses are integrated into a model of bilingual education in which educational outcomes are explained as a function of the interaction between background, child input and educational treatment factors. It is suggested that many evaluations of bilingual education programs have produced uninterpretable data because they have failed to incorporate the possibility of these interactions into their research designs.