This paper reports on a literacy pilot project which investigated the use of multilingual reading books and the pedagogical strategies that were employed by one bilingual teacher and her assistant to teach literacy in a linguistically diverse Grade 1 classroom in a primary school in the Western Cape, South Africa. Data were collected by means of classroom observations and semi-structured interviews to understand the teacher’s literacy instruction, reflecting her understanding of the multilingual pedagogical approach as a means of fostering learners’ biliteracy skills. Through the lens of the social constructivist theory and the notion of biliteracy, this paper argues that bilingual competence does not necessarily translate to biliteracy if the teaching approaches and learning materials are not systematically and adequately used to support learners’ listening, oral, reading and writing skills in different languages in an integrated and holistic manner in multilingual classrooms. It concludes that, despite the progressive South African Language-in-Education Policy which supports additive multilingualism, classroom practices continue to reinforce monolingualism in English, which deprives the majority of learners of meaningful access to literacy in different languages as they do not exploit the socio-cultural and cognitive capital embedded in the learners’ home languages for additive bilingual and biliteracy competence.