This paper seeks to reconstruct how the Latin (weak) personal pronouns were reanalyzed as verbal clitics in the Romance languages. As this process is strongly tied to word order phenomena, the first two sections study the positions which pronouns occupied in the sentence structure of Classical Latin and of Early Romance. This analysis is based on the reconstruction of sentence structure evolution proposed in Salvi (1999,2000). Section 3 discusses some differences between Latin and Romance atonic pronouns and concludes that they belonged to two different grammatical categories:Latin weak pronouns, were phrases, Romance clitics and heads/affixes. Finally, section 4 identifies the reasons for the diachronic reanalysis: in Vulgar Latin the obligatory expression of the core verbal arguments (probably a consequence of the loss of the Latin case system) strongly increased the occurrences of the weak pronouns, which, due to the changes in the sentence structure, were mainly adverbial. At the same time the evidence for their phrasal character was becoming so small, with he result that the pronouns, which mainly expressed the core arguments of the verb, were reanalyzed as adverbal heads.
