This book examines Latin word order, its historical origins in Proto-Indo-European and the shift in ordering patterns that took place in syntax and morphology in the history of Latin and (early) French (OV or left branching giving way to VO or right branching). Subsequently, analysis of the acquisition of ordering patterns shows that the archaic structuration—when complex—is acquired with difficulty. Diachronic and psycholinguistic analysis therefore demonstrates that the order of grammatical structures in Modern French, for example, is the result of a long-lasting development that psycholinguistic data can account for.