This project aligns with the multi-disciplinary approach characterising the most recent studies on non-literary and sub-standard (or “Vulgar”) Latin, as it aims to conjugate Latin epigraphy and modern Historical Sociolinguistics. In particular, this research will be devoted to determining whether a sociolinguistic variation (both stylistic, diastratic and diatopic) emerged within the “Vulgar” Latin vowel system and whether the relative chronology often assumed for the phonetic shifts [i, u] - [ɪ, ʊ] - [e, o] should be regarded as trustworthy. In order to investigate this issue, every instance of and graphemic oscillation occurring in Latin inscriptions from the city of Rome will be taken into account. At the same time, every “deviation” from the standard norm will be analysed in detail, considering the dating, typology and onomastic features of every inscription. Moreover, the collected data from Rome will be compared with other epigraphic data from Italy, using József Herman’s comparative method.