Social psychologists have suggested that language-based ideologies related to "stereotype threat" (i.e. variations in performance-based on ability perceptions of language groups) may affect students' academic achievement regardless of school language support. However, it is unclear whether efforts to support students' first language development, particularly for large populations of students whose primary language is not the dominant language, is sufficient for "levelling the playing field" in terms of academic achievement. We analysed subsets of data from the 2011 Progress in International Reading Literacy Study and the 2009 Programme for International Student Assessment to investigate the by-country effects of officially recognised languages on reading performance. Participants represent countries with only two official languages (e.g. Canada, Israel) and primarily used one of these languages at home. Preliminary findings from hierarchical linear modelling show that the dominant official language predicts reading performance unless the minority language reflects a language internationally valued and revered by local stake holders (e.g. English in the United Arab Emirates). Implications suggest that educational resources and programmes should be sensitive to the historical context of country-specific language ideologies and related stereotypical perceptions that favour the dominant language within the school context.