This paper analyses the controversial discourses around the significance of the Arabic language in Eritrea. It challenges the arguments of the government and some scholars, who claim that the Arabic language is alien to Eritrean society. They argue that it was introduced as an official language under British rule and is only spoken by the Rashaida minority and by a small educated elite. By contrast, this paper demonstrates that Arabic has served as the established lingua franca among the Eritrean Muslims and as the administrative language and medium of education for centuries. The main focus of the paper is a critique of the government's post-independence language policy, which replaced Arabic as the medium of instruction by mother tongue education under the purported aim of establishing the equality of all nine Eritrean languages. I argue that the promotion of this policy has political implications and that one of its purposes is to alienate the Muslim community from the use of the Arabic language as a marker of their common identity. The article is written from a sociological perspective and draws on numerous conversations with mother tongue school teachers, students and parents, and on participant observation of the public debate.