The Catalan second person singular (2sg) pronoun tu (you) has acquired a wide range of pragmatic values in spoken registers that have received little or no attention from scholars in the field. The aim of the present article is to analyse a particular emerging use of the 2sg pronoun tu from a corpus-based perspective. In the light of Grammaticalisation Theory, it is argued that whereas in some contexts this pronoun maintains all or part of its referential function (e.g. as subject or as a vocative, respectively), in other contexts its use is very similar to that of an emphatic pragmatic marker. Data drawn from three spoken corpora suggest that the pronoun has consolidated this new use. Prosodic evidence is also provided to show the semantic and pragmatic changes undergone by the pronoun.