In modelling the discourse–grammar interface, a central question concerns the status of discourse act as the minimal unit of discourse organization and its relation to units of grammatical structure. This paper seeks to clarify the notion of act by defining it as a strategic rather than a conceptual unit, and by setting out a classification of strategic acts. Illustration is then offered for the position that discourse acts are to a very considerable extent realized in English by intonation units and punctuation units. This is done by considering how punctuational variation and cases of intonation/syntax mismatch can be explained in terms of the specific discourse contribution of the units concerned. Although the correlation between discourse acts and intonation/punctuation units remains problematic, in that there may not be a 1 : 1 correspondence, it is still attractive — at least for English — to see the linguistic correlate of acts in intonation and punctuation units rather than in syntactic structures. The paper finishes by considering the implications for the formalizing of relations between discourse, semantics and syntax in Functional Discourse Grammar.