This paper examines variation and change in argument realization shown by the evolution of presentational, existential and event-reporting structures in the indigenous linguistic varieties of north-west Italy from the medieval period to the present. The common function of these constructions, namely the introduction of a new entity or situation into the world of discourse, both justifies their all being considered ‘presentational’ and accounts for the fact that their realizations in the vernaculars and dialects examined are historically related. The diachronic analysis discusses changes affecting three key morphosyntactic domains: (i) presence and role of a locative clitic; (ii) word order (preverbal vs. postverbal nominal subject/pivot); (iii) subject/pivot – verb agreement patterns, which eventually lead to the grammaticalization of dedicated presentational structures.