This article examines email exchanges between eight Master's-level school counseling student interns and their internship supervisor to investigate how politeness strategies contribute to professional identity development in supervisory discourse. Our analysis demonstrates how identity development occurs via collaborative facework accomplished through multiple strategies: reported speech or "constructed dialogue" (Tannen, 2007), first person plural pronouns, the discourse marker "that being said," and repetition. These strategies create supervisor-supervisee solidarity and build and display supervisee competence, while also creating a discursive web of relations among people that links supervisees into their professional "community of practice" (Lave & Wenger, 1991). This study thus provides a discursive, micro-level understanding of professional identity development and its theoretical underpinnings in the context of email supervision.