Academic writing is not a lifeless communicative endeavor. It is an interactive process where both writers and readers negotiate meanings in many complex ways. In the case of persuasive essays, students should venture to manifest stance and identity rather than just write to transport ideas. This paper looked into this important aspect of academic writing by examining the construction of writer identity in ESL students' persuasive essays. Data were drawn from 50 persuasive essays written by Filipino senior high school students in a polytechnic school. Using Hyland's (2004a) Model of Interpersonal Metadiscourse, analysis revealed that students employ "self-mention" across all samples in displaying their identity as writers. Findings also underscored the employment of other interpersonal metadiscourse elements such as "hedges," "attitude markers," "boosters," and "engagement markers" in student essays. The study echoes the following implications to L2 academic writing pedagogy: (1) L2 teachers may consider explicit instruction of metadiscourse markers in the classroom if students are to become effective writers; (2) students should be taught pragmatic functions of personal pronouns to help them carry out their stance in such a highly academic world of writing; and (3) more importantly, L2 writing teachers should employ more real-life and authentic writing activities which can foster the development of critical thinking skills and understanding of various contextualized linguistic elements. Moreover, directions for further research are provided in this research.