This paper explores how Culturally Sustaining Systemic Functional Linguistics (CSSFL), a theoretical and pedagogical approach, facilitates emergent bilingual (EB) students' engagement in explicit, equitable literacy practices within the unique context of a middle school intensive reading classroom. This design-based research (DBR) study documents the literacy practices and routines of EBs in a culturally and linguistically diverse intensive reading classroom, what CSSFL-informed lessons comprise when created in response to students' cultural and linguistic affordances, and how students' genre-based language knowledge was supported in these lessons. Culturally Sustaining Pedagogy and Systemic Functional Linguistics informed analysis of data collected from observations, student samples, researcher reflections, and video/audio-recordings. Findings indicate that while there were missed opportunities for culturally sustaining practices and explicit language instruction in the reading classroom, designing and implementing a CSSFL-informed and curriculum-aligned lessons facilitated students' enthusiasm and active participation, community building and shared experiences, and use of translanguaging and multimodal practices to heighten metalinguistic awareness.