This thesis investigates the expression of temporal reference – the location of eventualities (states and events) in time – in natural languages by looking at four languages: English, French, Italian and Romanian. It is suggested that temporal reference is determined at the discursive level through a large variety of linguistic and pragmatic means. The current state of the art on temporal reference lacks of a comprehensive cross-linguistically valid model that holds for typologically different languages, which goes beyond language specificities and which permits consistent contrastive analyses. The present study aims at filling in this gap by proposing a model of temporal reference situated in-between Theoretical and Applied Linguistics, Corpus Linguistics, Contrastive Analysis, Natural Language Processing and Machine Translation fields.