Language as the key to integration. General agreement on the mechanisms and social conditions of language acquisition. Conditions of national language acquisition. Competent bilingualism remains exceptional. A good knowledge of the national language is central to educational success. Unfavourable conditions are mutually reinforcing. Knowledge of the national language has a decisive influence on occupational opportunity. Bilingual skills do not (generally) pay off. Ethnic resources largely insignificant when it comes to educational and labour market success. Some differences between immigrants of different origin have not yet been clarified. Intergenerational integration, linguistic pluralism and ethnic differentiation.