The applicability of immersion education. One very successful bilingual programme is the immersion education practised in Canada, and Swain ( 1980) suggests that it might be applicable in other situations. In this programme, a group of children homogenous in its complete lack of knowledge of L2 is taught L2 as a medium by a bilingual teacher. The teacher understands the children's utterances in Ll but replies in L2. Thus the children first of all learn to comprehend L2. Ll is, however, later also incorporated into the program:1J1e, and both languages thereafter serve as languages of instruction throughout schooling. Swain does, however, point out that certain cri~eria have to be present if such a programme is to be successful. In the Canadian programme the parents belonged to the lin- guistic majority and wanted their children to learn French, on the condition that their ability in their native English was not impaired. In the case of a vernacular low in prestige, such a programme would probably lead to rapid assimilation, or, in Lamberfs words (1975), to "subtractive bilingualism" where competence is gained in L2 to the detriment of L1. Thus Swain concludes that such a programme could be successful in some instances, but not in all.