As part of a larger interview-based study of the beliefs, practices and experiences of 16 proofreaders of student writing in a university setting, this article reports informants' conceptualisations of their role. "Proofreading" is defined for the purposes of this research as "third-party interventions (that entail some level of written alteration) on assessed work in progress". Informants' descriptions were grouped using five metaphors to describe the proofreader's role: helper, cleaner, leveller, mediator and/or teacher. Although some informants did not identify with the proofreader-as-teacher metaphor, it turned out that proofreaders adopt a number of strategies to ensure their feedback is formative. The implications of the study are discussed, and further issues for research identified. (Contains 1 note.)