Skilled writers have at their disposal a range of rhetorical strategies for positioning themselves as competent members of a particular discourse community, including the judicious use of self-referential pronouns (e.g. "I," "she," "he") to overtly signal authorial presence. However, while researchers routinely recommend that second language (L2) writers receive instruction on the use of this rhetorical strategy, empirical studies on the effect of such instruction are rare. The present study investigates the effect of explicit instruction on the ability of non-native speakers of English (NNS) (n = 77) at two different levels of proficiency to use two signals of authorial presence (first person pronouns and self-referential third person pronouns/phrases) while writing specially constructed essay types. Using a controlled/posttest design with stimulated recall data, the study found that the instructed students significantly outperformed their non-instructed counterparts on Essay 1 (immediately after treatment), Essay 2 (one week later) and a quiz (one month later). The effect of the instruction did not depend on the proficiency of the student. Implications for L2 writing instruction are discussed. (Contains 1 table and 2 figures.)