The introduction enquires into the principal features of selected official language regimes within multilingual and multi-ethnic states. It defines key terms such as Official Bilingual Regime and presents a theoretical debate on the conceptual and methodological aspects of official language(s) policy. Secondly, it identifies the key questions and issues generated by the maturation of Official Language Regimes as perceived by politicians and decision-makers, senior public servants, civil society agencies and a range of scholars. Interviews and documentary analysis were carried out in eight jurisdictions ranging from Canada to Catalonia together with several international organisations and networks.