The current study builds on previous scholarship that examines the everyday language and literacy practices of linguistically diverse communities as resources for teaching and learning. It argues that only by valuing non-dominant linguistic practices in academic contexts will educators achieve equitable pedagogies that incorporate students' range of linguistic and literacy resources in the service of their learning. It adopts theoretical frameworks that conceptualize literacy as the reflection of particular social and cultural practices embedded in complex political, socially-situated spaces (Scribner, 1997; Cope & Kalantziz, 2009) to shed light on the untraditional, yet contextually-innovative literacy practices that heritage students deploy in a non-classroom academic context, many of which resemble the academic literacy demands of traditional classrooms. Arguing for the importance to critically examine bi/multilingual student practices in academic contexts, this study investigates the translingual academic literacy practices of a group of six undergraduate speakers of Spanish as a heritage language who work as academic peer tutors within a Spanish for Heritage Speakers Program at a large public university. This study uses ethnography methodologies as well as Conversational Analysis (CA) grounded in Appraisal Theory (an extension of Systemic Functional Linguistics) (Martin & White, 2005) to investigate tutors' contextually motivated use of language across transcriptions of tutoring session video recordings throughout 11 weeks (1 academic quarter). The analysis demonstrates that peer tutors mobilize translingual literacy practices with the two overarching goals of supporting their tutees' academic literacy and building community, illustrating the powerful impact of a student-led academic community. In all, this dissertation demonstrates that tutors' use of language mobilizes highly structured, socially-situated, semantic practices. By using social approaches to literacy to explore the language and literacy practices that heritage students deploy in a non-classroom academic context, this work presents counter-narratives that challenge the deficit discourse that has traditionally governed the dialogue around literacy instruction for multilingual students. [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.]