This book explores sets of movement cases in medieval Italian from 1200 to 1315. It offers an integrated description of all the relevant aspects of word order in Old Italian based on uniform principles (analysing the left periphery of the sentence, of the verbal phrase, and of the determiner phrase, and the interaction of these structures with quantification and negation). From the theoretical point of view, it considers the possibilities of a syntactic model in which the (left) edges of the constituents play an essential role in determining the possible structures. The author suggests that Old Italian has a rule preposing topic and focus elements to dedicated positions not only in the left periphery of the complementizer phase but also in the left periphery of other phases. She also provides an account of the apparent optional negative concord pattern exhibited by Old Italian in terms of dedicated positions. The book concludes with a summary of the various types of preposing presented in the book, arguing that all cases of optionality can be resolved within a single grammar and without need to resort to the double base hypothesis, which requires competence of the speakers on two different grammatical systems. The book makes important contributions to the medieval history of Italian, to Romance historical linguistics, and to the study of diachronic syntactic change more generally.