This book investigates the syntactic and semantic development of a selection of indefinite pronouns and determiners (such as aliquis 'some', nullus 'no', and nemo 'no one') between Latin and the Romance languages. Although these elements have undergone significant diachronic change since the Classical Latin period, the modern Romance languages show a remarkable degree of similarity in the way their systems of indefinites have evolved and are structured today. In this volume, Chiara Gianollo draws on data from Classical and Late Latin texts, and from electronic corpora of the early stages of various Romance languages, to propose a new account of these similarities. The focus is primarily on Late Latin: at this stage, the grammar of indefinites already shows a number of changes, which are homogeneously transmitted to the daughter languages, leading to parallelism in the various emerging Romance systems. The volume demonstrates the value of using methods and models from synchronic theoretical linguistics for investigating diachronic phenomena, as well as the importance of diachronic research in understanding the nature of crosslinguistic variation and language change.