In the historical development of many languages of the IE phylum the loss of inflectional morphology led to the development of a configurational syntax, where syntactic position marked syntactic role. The first of these configurations was the adposition (preposition or postposition), which developed out of the uninflected particle/preverbs in the older forms of IE, by forming fixed phrases with nominal elements, a pattern later followed in the development of a configurational NP (article + nominal) and VP (auxiliary + verbal). The authors follow this evolution through almost four thousand years of documentation in all twelve language families of the Indo-European phylum, noting the resemblances between the structure of the original IE case system and the systemic oppositions to be found in the sets of adpositions that replaced it. Quite apart from its theoretical analyses and proposals which in themselves amount to a new look at many traditional problems, this study has a value in the collected store of information on cases, and on adpositions and their usage. There is also a considerable store of etymological information that is relevant to the description of the systemic development.