Metadiscourse is self-reflective linguistic material referring to the evolving text and to the writer and imagined reader of that text. It is based on a view of writing as social engagement and in academic contexts reveals the ways that writers project themselves into their discourse to signal their attitude towards both the propositional content and the audience of the text. Despite considerable interest in metadiscourse by teachers and applied linguists, however, it has failed to achieve its explanatory potential due to a lack of theoretical rigour and empirical confusion. Based on an analysis of 240 L2 postgraduate dissertations totalling 4 million words, we offer a reassessment of metadiscourse, propose what we hope is a more robust model, and use this to explore how these students used metadiscourse. Essentially our argument is that metadiscourse offers a way of understanding the interpersonal resources writers use to present propositional material and therefore a means of uncovering something of the rhetorical and social distinctiveness of disciplinary communities.