§1. In the history of Low German the period from the beginning of the thirteenth century to about the middle of the sixteenth is called the middle period; the language of this period is Middle Low German. The substitution in the records, of the native idiom for Latin, marks the beginning of this period; the gradual shift to the use of High German marks its end. Written MLG experienced standardization (much as has NHG), but not to the point of absolute uniformity; local characteristics persist throughout the documents. By virtue of these localisms, even the most standardized written MLG falls into four dialectically colored types, which correspond to the indigenous dialect grouping of Westphalian, Eastphalian, North-Saxon (Nordniedersächsisch), and Brandenburgian. Of these, North-Saxon, extending over the coastal regions from Oldenburg, Bremen, Hamburg, and Lübeck, to Pomerania and beyond, acquired the greatest influence and importance, and the standardization of MLG writing was in the direction of the North-Saxon forms. It is generally supposed that the MLG written language of the East-Baltic territory (i.e., Estonia, Livonia, and Courland in the Middle Ages) belonged to the North-Saxon group. The evidence for this is still scanty; in this study I shall show that in at least one important set of records, the Baltic Low German of Riga (Latvia) shows the North-Saxon phonology. This set of records is the first of a series of Deed Registries (Erbebücher, official town-records of real-estate transfers) in the city archives of Riga.