This research is based on a longitudinal study of two categories of secondary high school pupils, a group involved in "European" programmes in different types of schools, comprehensive, technical and vocational, in which a school subject is taught through English, and a control group of pupils who follow a traditional curriculum in a French secondary school. After introducing the characteristics of the programmes, the local conditions and specificities of the schools in which the observations have taken place, and the pupils who have acted as informants in the research, this study moves on to an analysis of the pupils' written work in English and of the influence of the mental conceptions they hold of their learning rocesses and of the teaching they receive. The outcomes of the study are first that the communicative competence of European programme pupils does not seem to be notably more versatile or precise than the one developed by "ordinary" pupils, and then that direct experience of communicating in a foreign language has a significant cognitive impact on the language proficiency of adolescents in a school context.
