L2 writers likely perceive "good academic writing" as impersonal (Hyland, 2002; Shen, 1989; Tang & John, 1999). Yet research has shown that every linguistic and rhetorical choice that a writer makes--including, the presence/absence and different forms of self-mention--potentially reveals the writer's authorial identity (Ivanic, 1998). The dialogic nature of academic writing, as manifested in strategic self-mentions, has remained overshadowed in L2 writing pedagogy by other linguistic issues. This article draws attention to this gap in research: specifically, I report on the findings of a corpus-driven descriptive inquiry into authorial identity, operationalized as the use of first-person pronouns in a corpus of 126 argumentative research papers written by students enrolled in first-year L2 composition courses. The study examines how L2 writers practice self-mention, comparing the frequencies of first-person pronouns in the argumentative corpus with both a "parent" corpus, which contains other genres produced by the same group of writers, and published research analyzed by Hyland (2001). I also define and characterize the five qualitatively coded and quantitatively measured rhetorical functions of "I" used in the corpus (i.e., reporter, architect, narrator of personal experiences, conceder, and opinion-holder). L2 writers in this study were found to use self-mention more frequently than published authors. However, L2 writers employed self-reference less frequently in their argumentative essays than for other genres. Their argumentative texts reproduced a narrative tone, as indicated by the lower ratio of the subjective/objective case of the first-person singular pronoun. A comparison of rhetorical functions reveals that nearly 50% of "I"s in the corpus function as a "narrator of personal experiences." In light of the findings, I propose pedagogical suggestions aimed at more effectively socializing college-level L2 composition students into academic discourse communities.