Approaches in sociology of education suggest a major role for the school in social and cultural reproduction. In a bilingual setting involving a minority culture, bilingual schools-may operate minority cultural reproduction which is distinct and possibly counter to dominant cultural reproduction. Conflict over the establishment of bilingual schools in Wales is character-ised by ethnic alliances between class fragments, suggesting a n awareness of the schools' role in minority cultural reproduction. The schools are perceived of as successful, and opponents to the schools attribute their success to middle class bias in school intake. In order to investigate the different reasons £or the success of bilingual schools, the research involves a two stage a.nalysis of the designated bilinguaJ_ secondary schools. Stage 1 is based on data drawn from seven such schools, 2.nd is concerned to investigate social class and achievement in the schools. Considerable variation i s found between the schools in relation to both aspects, and particularly in relation to social class. Relating social class to achievement indicates that the above average achievement of the schools, measured by performance in public examinations, is not to be explained solely in terms of social class. Stage 2 is thus concerned to explore other possible reasons for the schools' success, primarily in terms of aspects of teacher and pupil commitment. This research stage involves a comparison of a designated bilingual secondary school and its 'partner' English medium school. Data based on teacher interviews suggest high levels of commitment to the Welsh language, bilingual education and their school among bilingual school teachers. Data based on pupil sample responses suggest commitment to the Welsh language and to school among bilingual school pupils. The findings intimate that the school's role as an agency of minority cultura l reproduction predisposes favourable attitude towards the language a.nd culture, which in turn may predispose teaching and learning commitment and the success of the bilingual school.