This paper compares one grammatical feature of metadiscourse, namely clauses with an anticipatory 'it' and extraposed subject, in two computerised text corpora, consisting respectively of published Business Studies journal articles and of MBA student dissertations written by non-native English speakers. The main differences between the two corpora are in the use of it-clauses to persuade readers of the validity of claims. Explanatory proposals refer to the different writer-reader relationships in journal articles and dissertations. Implications of the findings for the teaching of academic writing are discussed.