During the Post-Classical period (III BC - VI AD), Greek underwent significant changes in relation to its case-system, among which the development of the genitive case. Despite the importance of these changes in the history of the language, very few studies have investigated this phenomenon, focusing on the loss of the dative rather than on the different usages and the expansion of the genitive, which diachronically preceded it. In this project, I aim to provide the first complete picture of the paths and patterns of the genitive in Post-Classical Greek, taking into account its syntactic, semantic and sociolinguistic developments. To this end, I will consider a large corpus composed by literary texts as well as epigraphical and papyrological non-literary documents, and make use of the most recent digital tools in the domain of Greek linguistics. My analysis will not only shed some light on an understudied period of the Greek language, but also contribute to relevant aspects of case theory and historical sociolinguistics.