This paper addresses itself to the question of why the English language should have levelled almost all of its inflections, and what the relationship is between the breakdown of the case system and the rise of fixed word-order, prepositional phrases, and verb periphrases. The explanation proposed for the phenomenon of syntactic drift is considered superior to the traditional explanation of the erosive effect of phonological change, and to the postulation of a metacondition responsible for the proliferation of free-standing segments rather than bound morphemes. First of all it is shown that Old English and Modern English are structurally more similar than has traditionally been assumed, that changes evident in Modern English can be traced from the earliest documentations of Old English. It is further shown that the answer cannot be found within the history of English, but rather, that the independent but parallel developments which take place in related languages are due to the structural features of the protolanguage, in this case, the Indo-European protolanguage. Finally it is shown that, while word-order change is not the sole cause of syntactic changes, it can be called upon to relate many diachronic developments which have until now defied explanation. (Author/AM)