It is generally agreed that, of all the Romance languages, French differs most strongly from its Latin ancestor—but relatively little is known about how exactly this situation came about. The present volume provides fresh leads helping to answer this question, by offering a comprehensive account of the morpho-syntactic changes that took place during the transition from Latin to French, Empirically based on a corpus of Merovingian Latin and Old French texts from ca. 500 until 1250 AD, the quantitative and qualitative analysis covers topics such as the Tense-Aspect-Mood system, quantification, nominal determination, pronouns, subordination, word order, information structure and discourse organisation, while paying special attention to the sociolinguistic properties of each text, as well as to differences between text types and genres. The most innovative feature of the book is that all chapters are co-authored by specialists of Late Latin and of Old French, bringing together the expertise of what have traditionally been two separate research communities. The discussion is informed by the theoretical literature, but not biased towards a particular framework. The book should be of great interest to Latinists and Romanists alike, and, more generally, to historical linguists.