The Corpus of Historical Low German the first treebank of historical Low German (Old Saxon/OS and Middle Low German/MLG). Particularly the syntax of MLG still forms an urgent research desideratum (cf. already Peters 1973: 105). The project closeley collaborates with the (not parsed) Referenzkorpus Mittelniederdeutsch und Niederrheinisch (ReN), parsing selected texts to cover all subperiods, text types, and scribal languages of MLG; besides including the OS HeliPaD.