The purpose of this article is to examine mother tongue education in Arabic in relation to Arabic diglossia, and to discuss equity and social justice. To study the diglossic situation in Arabic and the space provided by the steering documents for language use and translanguaging in Swedish mother tongue classrooms, we investigate language policy regarding ideology, and practices. In the study, we employ nexus analysis to explore relationships between different policy levels in the context of Arabic mother tongue education within the Swedish education system. Through nexus analysis, we examined aspects of equity and social justice and found traces of both Arabic educational traditions about diglossia and conflicts between monolingual ideologies and translanguaging. The study supports previous research on issues of equity and social justice in mother tongue education and specifically highlights the problem that the curriculum for mother tongue Arabic does not address issues of linguistic variation. The study suggests that, in the case of mother tongue Arabic, a translanguaging pedagogy could provide both teachers and students with space to use their various linguistic resources. Thus, the mother tongue classroom could become equitable and socially just compared to what was observed in the studied case.