The so-called Central Plateau Dialects or simply Central Dialects belong to the South Median group of Northwest Iranian languages and are spoken in central Iran, where the prevailing language is Persian. Currently, vestiges of these dialects are limited to several dozen remote villages as well as to the older generation of the Jewish and Zoroastrian communities living in the cities and in diaspora. The dominant influence of Persian for more than a millennium has resulted in the ousting of the vernaculars not only in major towns but also in a majority of villages. Historical evidence suggests that Central Dialects were native to the entire central Iranian Plateau, larger towns included, until the late medieval period. The big shift may have taken place during and after the Safavid dynastic rule, perhaps as a result of forceful propagation of Shi'ism, among other economic and socio-political vicissitudes of those days. Concrete evidence becomes available only in the later nineteenth century when European travelers and local geographers began to report on the language situation of the area. These documents enable us to speculate on the patterns and rates of language shift in various regions speaking Central Dialects. This trend has been accelerating parallel with the enormous socio-economic changes in the last half century. In many villages the local dialect is moribund and becoming increasingly limited to the elders, and the extinction will be the inevitable result of the forces of modernization and globalization in general and the rapid expansion of Persian education and mass media in particular. This paper attempts to show the dynamics of language shift among Central Dialects. The possible causes of the shift within village communities is discussed, while the urban Jewish and Zoroastrian speakers receive individual attention. Part of the data comes from the author's own fieldwork.