In this paper I consider the definiteness effects which are found in Sardinian presentational structures. I argue that they result from well-formedness conditions on the encoding of information structure. In particular, two kinds of information are encoded in morphosyntax: on the one hand, the pragmatic relations between the denotata of the sentence constituents and the propositions in which they are arguments and predicates, and, on the other hand, the status of such denotata in the minds of the discourse participants (see Lambrecht 1994: 49). An RRG analysis in terms of non-derivational linking between semantics and syntax suggests that the syntax of existentials and locatives is irrelevant to agreement and the definiteness value of the nominal. The Sardinian evidence suggests that agreement can be subject to pragmatic constraints in dependent-marking languages, regardless of pro drop. Finally, Sardinian presentationals with activity predicates, which are allegedly rare across languages, are analysed in terms of pragmatically motivated exceptional mapping between semantics and syntax. This analysis is likely to apply to analogous constructions which occur in Romance. © The Philological Society 2004.