The Benjamín de Tudela Secondary School is a state school with a British Council type bilingual section in compulsory secondary education, a French bilingual section in compulsory secondary education and a Bachibac section in non-compulsory secondary education. The teacher training centre is a state institution which belongs to the Navarrese Education Department. It organises the teacher training for around 1,500 teachers below university level in the Tudela area. The project we have developed is entitled “Teacher training – the key to success for student improvement in the bilingual sections of the Benjamín de Tudela secondary school”. On the one hand, the teacher trainers have improved their professional competence, and therefore have been able to design teacher training activities to suit the needs of teachers in bilingual sections best. On the other hand, the participating teachers from the Benjamín de Tudela secondary school have fostered their own linguistic, didactic and scientific competences. At present, and due to the generalisation of bilingual programs in Navarrese primary schools, secondary schools are in the process of receiving an increasing number of students in their bilingual sections. This generalisation of programs, the huge increase in numbers of students and the enormous variety of profiles in those students has brought about significant changes in bilingual teachers, who need to update their teaching practice. Seven professionals have taken part in this project –one language teaching specialist from the Foreign Language Section at the Navarrese Department of Education, two teacher trainers from the Tudela Teacher Training Section, two teachers from the French bilingual section and bachibac section, two teachers from the British Council bilingual section and one teacher teaching her subject in English, all of them at the Benjamín de Tudela secondary school. The teacher trainers and the teachers have attended seven structured courses. We are persuaded that taking part in the selected courses in a European context and the subsequent design of specific teacher training activities by the teacher trainers will significantly improve our students’ performance.