In the first part of the article, an approach to Greek diglossia is proposed, focusing on the differing social functions of the two coexisting Greek languages. The adoption of “pure” Greek in the early 19th century represented a compromise, which made possible the rejection of Ancient Greek as the official language of the new state. The language question that developed at the turn of the century represented an effort to modernize Greek culture in the context of economic and social change brought about by the rise of the bourgeoisie. Starting in the interwar period and increasingly after the civil war, “pure” Greek became associated exclusively with authoritarian politics. The language reform of 1976, which formally abolished diglossia, thus came at the end of a long process of devaluation of the official “pure” language. Yet, in recent years, a metalinguistic prophecy of language decline has received widespread acceptance. The second half of the article examines the reasons for its success and the resulting revival of the argumentation questioning Demotic Greek, and concludes that they should be attributed to a crisis of national identity. (Diglossia, language ideology, language planning, Greek)