The 20th century

At the start of the 20th century, Yiddish was emerging as a major Eastern European language. Its rich literature was ever more widely published, Yiddish theater and Yiddish film were booming, and it had even achieved status as one of the official languages of the Belorussian SSR. Educational autonomy for Jews in several countries (notably Poland) after World War I led to an increase in formal Yiddish-language education, more uniform orthography, and to the 1925 founding of the Yiddish Scientific Institute, later YIVO Institute for Jewish Research. Yiddish emerged as the national language of a large Jewish community in Eastern Europe that rejected Zionism and sought to obtain Jewish cultural autonomy in Europe. It also contended with Modern Hebrew as a literary language among Zionists.

On the eve of World War II, there were between 11 and 13 million Yiddish speakers (Jacobs 2005). The Holocaust, however, led to a dramatic, sudden decline in the use of Yiddish, as the extensive Jewish communities, both secular and religious, that used Yiddish in their day-to-day life were largely destroyed. Although millions of Yiddish speakers survived the war (including nearly all Yiddish speakers in the Americas), further assimilation in countries such as the United States, Soviet Union and the strictly monolingual stance of the Zionist ideology led to a decline in the use of Eastern Yiddish similar to the earlier decline in Western Yiddish. Nevertheless, the number of speakers within the widely spread Orthodox (mainly Hasidic) communities has lately been steadily on the rise. Although used in various countries, Yiddish has attained an official status of a minority language only in Moldova and Sweden.

Reports of the number of current Yiddish speakers vary significantly. Ethnologue estimates that in 2005 there were 3 million speakers of Eastern Yiddish,^[1] of which over one third lived in the United States. In contrast, the Modern Language Association reports fewer than 200,000 in the United States.^[2] Western Yiddish, which had "several tens of thousands of speakers" on the eve of the Holocaust, is reported by Ethnologue to have had an "ethnic population" of slightly below 50,000 in 2000 ^[3]. Intermediate estimates are also given, for example, of a worldwide Yiddish-speaking population of about 2 million in 1996 in a report by the Council of Europe.^[4] Further demographic information about the recent status of what is treated as an Eastern-Western dialect continuum is provided in the YIVO Language and Cultural Atlas of Ashkenazic Jewry (LCAAJ).

There have been frequent episodes of debate about the extent of the linguistic independence of Yiddish from the languages that it absorbed. Some commentary dismisses Yiddish as a mere jargon, although precisely that term, in Yiddish, is also used as a colloquial designation for the language, but without pejorative connotation. There have been periodic assertions that it is a German dialect and, even when recognized as an autonomous language, it has sometimes been referred to as Judeo-German. A widely cited statement of the situation in the 1930s was published by Max Weinreich, quoting a remark by an auditor of one of his lectures: אַ שפּראַך איז אַ דיאַלעקט מיט אַן אַרמיי און פֿלאָט (a shprakh iz a dialekt mit an armey un flot). "A language is a dialect with an army and navy" facsimile excerpt at discussed in detail in a separate article).