Underpinned by positioning theory as both a theoretical lens and methodological tool, this paper asserts that educators can improvise asset-based discourse to create spaces for student writers to exercise agency. This single-case study, focusing on four education undergraduates situated as both writers and writing mentors in a literacy course and after-school writing club with fourth and fifth graders, examined how their identities influenced their current positioning-of-self and other in relation to vulnerability and agency. I conducted positioning analysis of their identity-based poetry, autobiographical short stories, online course discussions, and written reflections. The findings demonstrate that participants who were more comfortable being vulnerable as writers used more asset-based language in their positioning-of-self and other compared to those that were less comfortable being vulnerable as writers. Additionally, undergraduates who felt more comfortable being vulnerable reported finding a new sense of appreciation for revision and acknowledged vulnerability as a challenging but important variable in their cultural identity constructions as writers and mentors. The discourse of course instructors filtered through pedagogy of vulnerability and their critical stances as educational researchers, created agentive positions for undergraduates to embody and disrupt conventional notions of what it means to be a writer and mentor. This study offers insight into two under explored areas, creative writing instruction based on pedagogies of vulnerability and the agentive and linguistic nature of positioning in higher education literacy courses and K-12 classrooms. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]