Using the tenets of translanguaging and with a focus on Arabic as a diglossic language, we examine the fluid and dynamic practices that transcend the boundaries between/among Standard Arabic, Arabic dialects, and English in content-based instruction in an advanced Arabic literature course. Using conversation analysis, we show how translingual practices in learner-learner and teacher-learner interactions and discussions utilize the available linguistic repertoires in the classroom discourse. These practices broke the priori established boundaries that set Standard Arabic as the target language. The use of Arabic dialects and English in the literature course promoted the negotiation of complex concepts, facilitated the engagement with and critical interpretation of literary texts, and enhanced the meaning-making process at large. The utilization of these translingual practices has maximized Arabic learners' gains. The article theoretically enriches recent discussions about the role of available linguistic repertoires in the ideological divide between language and content courses in language programs. It also advances the position that pedagogical translanguaging destabilizes the status of standard varieties as the target in diglossic languages.