We may justifiably assume that 18th century German-Latvian dictionaries display both traditional and regional features of dual-language lexicography involving German. The present study draws on the findings of contact linguistics and sets out to define the place of one such dictionary (J. Lange's »Lexicon«) within this tradition of two-way lexicography and to pinpoint its regional characteristics. The results demonstrate that the work was influenced by the design of one-language German dictionaries. Its regional nature manifests itself in the vocabulary (e.g. handling of separable prefix verbs) and is grounded in influences from Lower German and Latvian.