At first glance, the development of the Romance and Germanic have-perfects would seem to be well understood. The surface form of the source syntagma is uncontroversial and there is an abundant, inveterate literature that analyzes the emergence of have as an auxiliary. The "endpoints" of the development may be superficially described as follows (for English): (1) OE Ic hine ofslaegenne haebbe > Eng I have slain him The traditional view is that the source syntagma, <have + noun.ACC + perfect participle>, is structured [have [noun participle]], and that this syntagma undergoes change as have loses its possessive meaning. In this dissertation, I demonstrate that the traditional view is untenable and readdress two fundamental questions about the development of have-perfects: (i) how is the early ability of have to predicate possession connected with its later role in the perfect?; (ii) what are the syntactic structures and meanings of <have + noun.ACC + perfect participle> before the emergence of the have-perfect? With corpus evidence, I show that that the surface string <have + noun.ACC + perfect participle> corresponds to three different structures in Old English and Latin; all of these survive into modern English and the Romance languages. I propose that the likeliest source of the have-perfect is the structure exemplified in: (2) Now he has his opponent cornered. Sentences like (2), amply attested in Latin and Old English, contain an aspectual periphrasis that potentially describes two stages of a complex situation: the subject?s achievement of a result and a persisting resultant state. I hypothesize that the structure exemplified in (2) only became available after have had undergone semantic widening and entered into a systematic association with other expressions of possession and pertaining. I also devote considerable attention to the differing values <have + perfect participle>. Though English and the Romance languages all have a formally equivalent verbal construction, the time reference of this "same" construction varies significantly across languages. I argue that the value of <have + perfect participle> in a given language is best understood, synchronically and diachronically, in terms of the values of the verb forms that it complements.