In a multilingual society, the role of each language is parallel to the importance of the community that speaks it; change in power relations between groups is linked to modifications in the status of their language. The Quebec language laws provide a case in point of the relation between social change and language planning. This comprehensive analysis of the Quebec language issue exposes the material and symbolic causes of these legislative measures and assesses their effects. This detailed appraisal also provides answers to more general questions of the nature of language laws and the conditions for their legitimacy.