The study is based on the Bochum Middle High German Corpus, and in three steps it profiles the manifestations and characteristics of prepositions and prepositional phrases in Middle High German (1070?1350), the three levels being the inventory and variation at the word level, the structure of the prepositional phrase and the function of the phrase in the sentence. The study thus provides a systematic analysis of the phenomenon ‘preposition’ on the basis of a structured corpus of an historical stage in the development of German.