The paper deals with the system of palatal consonants: /t’/, /d’/, /n’/ in Low German, Prussian dialects of the Mennonites. This dialect was used in the “language islands” of the Ukraine and of several other regions of the Russian state and is today common in the Mennonite communities all around the world: Canada, USA, South America, Germany, Siberia and the Altai region. The research is based on the recent records of these dialects as well as on the data from the dialectal archive of Viktor Schirmunski (Žirmunskij) in St Petersburg. The rendering of the palatal consonants in the questionnaires in this archive by the dialect speakers in 1920s is examined. The palatalization of consonants in Plautdietch is considered from the background of the palatalizations and assibilations in the Ingvaeonic branch of West Germanic languages. It is emphasized that the palatalization is one of the characteristic phenomena of the Ingvaeonic languages, which can manifest itself in different periods of their history. Thus the development of the palatal consonants can be considered in the framework of genetically related languages’ typology. It is known that the palatalization of [k] and [g] occurred in Old English before and after front vowels. In Frisian, palatalization was followed by assibilation. In Dutch, palatalization is observed in the diminutive suffix. Palatalization in a number of Low German dialects occurred as well and was followed by zetacism. Thus the palatalizaion reflects internal trends in the development of the dialects of some West Germanic languages, namely those of the Ingvaeonic group. It is probably an intermediate stage preceding assibilation and affrication of consonants. In some cases it remains in the modern language in its initial state, as is the case in the Mennonite dialect of the Plautdietch.