Emergent bilingual students in the U.S. often attend English‐medium schools where their bi‐ and multi‐lingual language resources are ignored and dismissed. This article draws on a social literacies perspective to explore how a second‐grade teacher and her multilingual students re‐framed one English‐medium classroom to welcome and include biliterate composing practices, in opposition to monoglossic norms. Findings illustrate moves made by a teacher to launch new biliterate writing practices, including talking about rationales, and providing invitations, support, and recognition for bilingual composing. In particular, analyses show that talking about rationales or reasons for biliterate composing was central to disrupting English‐only discourses and instead building new ways of thinking about and enacting bilingual writing. Analyses then trace intercontextual connections across events to illustrate how repeated, connected talk about these rationales over time opened spaces for students to take up bilingual composing practices. The article concludes by discussing implications for teachers and researchers who are interested in supporting emergent bilingual students’ bi‐ and multi‐lingual language use in English‐medium schools.