Plautdiitsch, the language used by Menno-nites in many parts of the world, is a descendant of the West Prussian Low German dia-lects once spoken in the Weichsel delta area. Many of its characteristiscs can be explai-ned by the two centuries of isolati-on from other (Low) German dialects and by con-tacts with other languages, especially Russian. The Altai dialect of Plautdiitsch, although still mutually intelligible with other varieties of the language, shows a number of peculiarities. Some of these are developments of traits common to all Plautdiitsch dialects, others have arisen as a result of the increasingly intensive contacts with the Russian speaking surroundings. Apart from a short historical introduction, The Altai Dialect of Plautdiitsch consists of two parts. The first contains chapters on phonetics and phonology, the place of the Altai dialect in the Plautdiitsch diasystem, morfology (the case system), syntax (the auxiliary d\\246une 'to do'), contact phenomena (elements from Germanic and Slavonic languages; code switching), and orthography. The second part contains interviews in Plautdiitsch with an English translation. Topics discussed by the informants include the history of the Mennonites in Russia, everyday life in Siberia, contacts with other ethnic Germans and Russians, and emigration to Germany.